End effector control and calibration

ABSTRACT

Methods and apparatus for end effector control and calibration are described. The method may include detecting a signal in response to movement of a first tube relative to a second tube, the first tube driving movement of a clamp arm of the end effector. The method may further include determining a clamp arm position of the end effector relative to a ultrasonic blade of the end effector based on the signal. The method may also include adjusting a power output to the ultrasonic blade of the end effector based on the clamp arm position.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application claiming priority under35 U.S.C. § 120 to U.S. patent application Ser. No. 15/363,244, entitledEND EFFECTOR CONTROL AND CALIBRATION, filed on Nov. 29, 2016, now U.S.Patent Application Publication No. 2018/0146976, the entire disclosureof which is hereby incorporated by reference herein.

TECHNICAL FIELD

The technical field may generally relate to controlling surgicalinstruments, and in particular, controlling and calibrating endeffectors of surgical instruments.

BACKGROUND

Various aspects are directed to surgical instruments, and controllingand calibrating end effectors of surgical instruments.

For example, ultrasonic surgical devices are finding increasinglywidespread applications in surgical procedures by virtue of their uniqueperformance characteristics. Depending upon specific deviceconfigurations and operational parameters, ultrasonic surgical devicescan provide substantially simultaneous transection of tissue andhomeostasis by coagulation, desirably minimizing patient trauma. Anultrasonic surgical device may comprise a handpiece containing anultrasonic transducer, and an instrument coupled to the ultrasonictransducer having a distally mounted end effector (e.g., an ultrasonicblade and a clamp arm, where the clamp arm may comprise a non-sticktissue pad) to cut and seal tissue. In some cases, the instrument may bepermanently affixed to the handpiece. In other cases, the instrument maybe detachable from the handpiece, as in the case of a disposableinstrument or an instrument that is interchangeable between differenthandpieces. The end effector transmits ultrasonic energy to tissuebrought into contact with the end effector to realize cutting andsealing action. Ultrasonic surgical devices of this nature can beconfigured for open surgical use, laparoscopic, or endoscopic surgicalprocedures including robotic-assisted procedures.

Ultrasonic energy cuts and coagulates tissue using temperatures lowerthan those used in electro surgical procedures. Vibrating at highfrequencies (e.g., 55,500 times per second), the ultrasonic bladedenatures protein in the tissue to form a sticky coagulum. Pressureexerted on tissue by the ultrasonic blade surface collapses bloodvessels and allows the coagulum to form a hemostatic seal. A surgeon cancontrol the cutting speed and coagulation by the force applied to thetissue by the end effector, the time over which the force is applied andthe selected excursion level of the end effector.

SUMMARY

In one aspect, a method for controlling an end effector may includedetecting a signal in response to movement of a first tube relative to asecond tube, the first tube driving movement of a clamp arm of the endeffector. The method may also include determining a clamp arm positionof the end effector relative to a ultrasonic blade of the end effectorbased on the signal. The method may additionally include adjusting apower output to the ultrasonic blade of the end effector based on theclamp arm position.

One or more of the following features may be included. The first tubemay be an inner tube and the second tube may be an outer tube, the innertube being moveable relative to the outer tube, the outer tube beingstatic relative to the inner tube. The method may further includedetecting the signal using a Hall-effect sensor and a magnet positionedon the first tube. The method may also include moving a magnetpositioned on the first tube relative to a Hall-effect sensor as thefirst tube drives movement of the clamp arm of the end effector. Themethod may additionally include adjusting the power output to theultrasonic blade of the end effector using an ultrasonic transducerbased on a voltage change in a Hall-effect sensor. Moreover, the methodmay include adjusting the power output to the ultrasonic blade of theend effector dynamically, based on a travel ratio that changes as theclamp arm approaches the ultrasonic blade. Further more, the method mayinclude adjusting the power output to the ultrasonic blade of the endeffector dynamically, using a proportional-integral controller, based ona travel ratio that changes as the clamp arm approaches the ultrasonicblade.

In one or more implementations, the method may include determining atype of tissue between the clamp arm and the ultrasonic blade based onthe signal. The method may also include adjusting the power output tothe ultrasonic blade of the end effector based on the type of tissue.The method may additionally include, in response to determining that thetype of tissue between the clamp and the ultrasonic blade is a smallvessel, reducing the power output to the ultrasonic blade of the endeffector by an amount less than for a large vessel. Moreover, the methodmay include in response to determining that the type of tissue betweenthe clamp and the ultrasonic blade is a large vessel, reducing the poweroutput to the ultrasonic blade of the end effector by an amount morethan for a small vessel.

In one aspect, an apparatus for controlling an end effector may includea sensor configured to detect a signal in response to movement of afirst tube relative to a second tube, the first tube driving movement ofa clamp arm of the end effector. The apparatus may also include aprocessor configured to determine a clamp arm position of the endeffector relative to a ultrasonic blade of the end effector based on thesignal. The apparatus may further include a transducer configured toadjust a power output to the ultrasonic blade of the end effector basedon the clamp arm position.

One or more of the following features may be included. The first tubemay be an inner tube and the second tube may be an outer tube, the innertube being moveable relative to the outer tube, the outer tube beingstatic relative to the inner tube. The apparatus may further include amagnet positioned on the first tube wherein the sensor is a Hall-effectsensor used to detect the signal based on a position of the magnet. Themagnet may be positioned on the first tube moves relative to aHall-effect sensor as the first tube drives movement of the clamp arm ofthe end effector. The transducer may be an ultrasonic transducerconfigured to adjust the power output to the ultrasonic blade of the endeffector based on a voltage change in a Hall-effect sensor. Theapparatus may also include a proportional-integral controller configuredto adjust the power output to the ultrasonic blade of the end effectordynamically, based on a travel ratio that changes as the clamp armapproaches the ultrasonic blade.

In one aspect, a method for calibrating an apparatus for controlling anend effector may include detecting a first signal corresponding to afully open position of a clamp arm and a ultrasonic blade of the endeffector. The method may also include detecting a second signalcorresponding to an intermediate position of the clamp arm and theultrasonic blade of the end effector, the intermediate positionresulting from clamping a rigid body between the clamp arm and theultrasonic blade. The method may additionally include detecting a thirdsignal corresponding to a fully closed position of the clamp arm and theultrasonic blade of the end effector. The method may further includedetermining a best fit curve to represent signal strength as a functionof sensor displacement based on at least the first, second, and thirdsignals, the fully open, intermediate, and fully closed positions, and adimension of the rigid body. Moreover, the method may include creating alookup table based on at least the first, second, and third signals, andthe fully open, intermediate, and fully closed positions.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will become apparent from the description, the drawings, andthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of an example surgical instrument inaccordance with one aspect of the present disclosure

FIG. 2 is a perspective view of an example surgical instrument inaccordance with one aspect of the present disclosure;

FIG. 3 illustrates an example end effector of a surgical instruments inaccordance with one aspect of the present disclosure;

FIG. 4 illustrates an example end effector of a surgical instruments inaccordance with one aspect of the present disclosure;

FIG. 5 is an exploded view of one aspect of a surgical instrument inaccordance with one aspect of the present disclosure;

FIG. 6 illustrates a diagram of a surgical instrument in accordance withone aspect of the present disclosure;

FIG. 7 illustrates a structural view of a generator architecture inaccordance with one aspect of the present disclosure;

FIGS. 8A-8C illustrate functional views of a generator architecture inaccordance with one aspect of the present disclosure;

FIG. 9 illustrates a controller for monitoring input devices andcontrolling output devices in accordance with one aspect of the presentdisclosure;

FIGS. 10A and 10B illustrate structural and functional aspects of oneaspect of the generator in accordance with one aspect the presentdisclosure;

FIG. 11 illustrates an example end effectors and shaft of a surgicalinstrument in accordance with one aspect of the present disclosure;

FIG. 12 illustrates an example Hall-effect sensor and magnetconfiguration in accordance with one aspect of the present disclosurewhere the Hall-effect sensor is fixed and the magnet moves in a lineperpendicular to the face of the Hall sensor;

FIG. 13A illustrates an example Hall-effect sensor and magnetconfiguration in accordance with one aspect of the present disclosurewhere the Hall-effect sensor is fixed and the magnet moves in a lineparallel to the face of the Hall-effect sensor;

FIG. 13B illustrates an example Hall-effect sensor and magnetconfiguration in accordance with one aspect of the present disclosurewhere the Hall-effect sensor is fixed and the magnet moves in a lineparallel to the face of the Hall-effect sensor;

FIG. 14A is a table of output voltage of a Hall-effect sensor as afunction of distance as a clamp arm moves from a fully closed positionto a fully open position in accordance with one aspect the presentdisclosure;

FIG. 14B is a graph of output voltage of a Hall-effect sensor as afunction of distance as a clamp arm moves from a fully closed positionto a fully open position in accordance with one aspect the presentdisclosure;

FIG. 15A is a top view of a Hall-effect sensor and magnet configurationsin a surgical instrument and corresponding open jaws end effectorposition in accordance with one aspect of the present disclosure;

FIG. 15B is a top view of a Hall-effect sensor and magnet configurationsin a surgical instrument and corresponding closed jaws end effectorposition in accordance with one aspect of the present disclosure;

FIG. 16 illustrates a plan view of a system comprising a Hall-effectsensor and magnet configuration in a surgical instrument in accordancewith one aspect of the present disclosure;

FIG. 17A illustrates a view of an Hall-effect sensor and magnetconfigurations in the context of a surgical instrument in accordancewith one aspect of the present disclosure;

FIG. 17B illustrates a view of an Hall-effect sensor and magnetconfigurations in the context of a surgical instrument in accordancewith one aspect of the present disclosure;

FIG. 18 illustrates a Hall-effect sensor and magnet configuration in asurgical instrument in accordance with one aspect of the presentdisclosure;

FIG. 19A illustrates a Hall-effect sensor and magnet configuration inaccordance with one aspect of the present disclosure;

FIG. 19B illustrates Hall-effect sensor and magnet configurations in asurgical instrument in accordance with one aspect of the presentdisclosure;

FIG. 20 is a graph of a curve depicting Travel Ratio (TR) along they-axis, based on Hall-effect sensor output voltage, as a function ofTime (Sec) along the x-axis in accordance with one aspect of the presentdisclosure;

FIG. 21 illustrates a graph of a first curve depicting Travel Ratio (TR)along the left y-axis, based on Hall-effect sensor output voltage, as afunction of Time (Sec) along the x-axis in accordance with one aspect ofthe present disclosure;

FIG. 22 illustrates charts showing Proportional-Integral control ofpower output to an ultrasonic blade in accordance with one aspect of thepresent disclosure;

FIG. 23 illustrates several vessels that were sealed using thetechniques and features described herein in accordance with one aspectof the present disclosure;

FIG. 24 illustrates a graph of a best fit curve of Hall-effect sensoroutput voltage as a function of distance for various positions of theclamp arm as the clamp arm moves between fully closed to a fully openpositions in accordance with one aspect of the present disclosure;

FIGS. 25-28 illustrate an end effector being calibrated in fourdifferent configurations in accordance with various aspects of thepresent disclosure using gage pins for two of the configurations forrecording a Hall-effect sensor response corresponding to variouspositions of the clamp arm to record four data points (1-4) to create abest fit curve during production, where:

FIG. 25 illustrates an end effector in a fully open configuration torecord a first data point (1) in accordance with one aspect of thepresent disclosure;

FIG. 26 illustrates an end effector in a second intermediateconfiguration grasping a first gage pin of a known diameter to record asecond data point (2) in accordance with one aspect of the presentdisclosure;

FIG. 27 illustrates an end effector in a third intermediateconfiguration grasping a second gage pin of a known diameter to record athird data point (3) in accordance with one aspect of the presentdisclosure; and

FIG. 28 illustrates an end effector in a fully closed configuration torecord a fourth data point (4) in accordance with one aspect of thepresent disclosure;

FIGS. 29A-D illustrate an example surgical instrument in accordance withone aspect of the present disclosure and charts showing example outputpower level in a hemostasis mode for small and large vessels, where:

FIG. 29A is a schematic diagram of surgical instrument configured toseal small and large vessels in accordance with one aspect of thepresent disclosure;

FIG. 29B is a diagram of an example range of a small vessel and a largevessel and the relative position of a clamp arm of the end effector inaccordance with one aspect of the present disclosure;

FIG. 29C is a graph that depicts a process for sealing small vessels byapplying various ultrasonic energy levels for a different periods oftime in accordance with one aspect of the present disclosure; and

FIG. 29D is a graph that depicts a process for sealing large vessels byapplying various ultrasonic energy levels for different periods of timein accordance with one aspect of the present disclosure;

FIG. 30 is a logic diagram illustrating an example process fordetermining whether hemostasis mode should be used, in accordance withone aspect of the present disclosure;

FIG. 31 is a logic diagram illustrating an example process for endeffector control in accordance with one aspect of the presentdisclosure;

FIG. 32 is a logic diagram illustrating an example process forcalibrating an apparatus for controlling for an end effector inaccordance with one aspect of the present disclosure;

FIG. 33 is a logic diagram of a process for tracking wear of the tissuepad portion of the clamp arm and compensating for resulting drift of theHall-effect sensor and determining tissue coefficient of friction inaccordance with one aspect of the present disclosure;

FIG. 34 illustrates a Hall-effect sensor system that can be employedwith the process of FIG. 33 in accordance with one aspect of the presentdisclosure; and

FIG. 35 illustrates one aspect of a ramp type counter analog-to-digitalconverter (ADC) that may be employed with the Hall-effect sensor systemof FIG. 34 in accordance with one aspect of the present disclosure.

DESCRIPTION

Various aspects described herein are directed to surgical instrumentscomprising distally positioned, articulatable jaw assemblies. The jawassemblies may be utilized in lieu of or in addition to shaftarticulation. For example, the jaw assemblies may be utilized to grasptissue and move it towards an ultrasonic blade, RF electrodes or othercomponent for treating tissue.

In one aspect, a surgical instrument may comprise an end effector withan ultrasonic blade extending distally therefrom. The jaw assembly maybe articulatable and may pivot about at least two axes. A first axis, orwrist pivot axis, may be substantially perpendicular to a longitudinalaxis of the instrument shaft. The jaw assembly may pivot about the wristpivot axis from a first position where the jaw assembly is substantiallyparallel to the ultrasonic blade to a second position where the jawassembly is not substantially parallel to the ultrasonic blade. Inaddition, the jaw assembly may comprise first and second jaw membersthat are pivotable about a second axis or jaw pivot axis. The jaw pivotaxis may be substantially perpendicular to the wrist pivot axis. In someaspects, the jaw pivot axis itself may pivot as the jaw assembly pivotsabout the wrist pivot axis. The first and second jaw members may bepivotably relative to one another about the jaw pivot axis such that thefirst and second jaw members may “open” and “close.” Additionally, insome aspects, the first and second jaw members are also pivotable aboutthe jaw pivot axis together such that the direction of the first andsecond jaw members may change.

Reference will now be made in detail to several aspects, includingaspects showing example implementations of manual and robotic surgicalinstruments with end effectors comprising ultrasonic and/or electrosurgical elements. Wherever practicable similar or like referencenumbers may be used in the figures and may indicate similar or likefunctionality. The figures depict example aspects of the disclosedsurgical instruments and/or methods of use for purposes of illustrationonly. One skilled in the art will readily recognize from the followingdescription that alternative example aspects of the structures andmethods illustrated herein may be employed without departing from theprinciples described herein.

FIG. 1 is a right side view of one aspect of an ultrasonic surgicalinstrument 10. In the illustrated aspect, the ultrasonic surgicalinstrument 10 may be employed in various surgical procedures includingendoscopic or traditional open surgical procedures. In one aspect, theultrasonic surgical instrument 10 comprises a handle assembly 12, anelongated shaft assembly 14, and an ultrasonic transducer 16. The handleassembly 12 comprises a trigger assembly 24, a distal rotation assembly13, and a switch assembly 28. The elongated shaft assembly 14 comprisesan end effector assembly 26, which comprises elements to dissect tissueor mutually grasp, cut, and coagulate vessels and/or tissue, andactuating elements to actuate the end effector assembly 26. The handleassembly 12 is adapted to receive the ultrasonic transducer 16 at theproximal end. The ultrasonic transducer 16 is mechanically engaged tothe elongated shaft assembly 14 and portions of the end effectorassembly 26. The ultrasonic transducer 16 is electrically coupled to agenerator 20 via a cable 22. Although the majority of the drawingsdepict a multiple end effector assembly 26 for use in connection withlaparoscopic surgical procedures, the ultrasonic surgical instrument 10may be employed in more traditional open surgical procedures and inother aspects, may be configured for use in endoscopic procedures. Forthe purposes herein, the ultrasonic surgical instrument 10 is describedin terms of an endoscopic instrument; however, it is contemplated thatan open and/or laparoscopic version of the ultrasonic surgicalinstrument 10 also may include the same or similar operating componentsand features as described herein.

In various aspects, the generator 20 comprises several functionalelements, such as modules and/or blocks. Different functional elementsor modules may be configured for driving different kinds of surgicaldevices. For example, an ultrasonic generator module 21 may drive anultrasonic device, such as the ultrasonic surgical instrument 10. Insome example aspects, the generator 20 also comprises anelectrosurgery/RF generator module 23 for driving an electrosurgicaldevice (or an electro surgical aspect of the ultrasonic surgicalinstrument 10). In the example aspect illustrated in FIG. 1, thegenerator 20 includes a control system 25 integral with the generator20, and a foot switch 29 connected to the generator via a cable 27. Thegenerator 20 may also comprise a triggering mechanism for activating asurgical instrument, such as the instrument 10. The triggering mechanismmay include a power switch (not shown) as well as a foot switch 29. Whenactivated by the foot switch 29, the generator 20 may provide energy todrive the acoustic assembly of the surgical instrument 10 and to drivethe end effector 18 at a predetermined excursion level. The generator 20drives or excites the acoustic assembly at any suitable resonantfrequency of the acoustic assembly and/or derives thetherapeutic/sub-therapeutic electromagnetic/RF energy. In one aspect,the electrosurgical/RF generator module 23 may be implemented as anelectrosurgery unit (ESU) capable of supplying power sufficient toperform bipolar electrosurgery using radio frequency (RF) energy. In oneaspect, the ESU can be a bipolar ERBE ICC 350 sold by ERBE USA, Inc. ofMarietta, Ga. In bipolar electrosurgery applications, as previouslydiscussed, a surgical instrument having an active electrode and a returnelectrode can be utilized, wherein the active electrode and the returnelectrode can be positioned against, or adjacent to, the tissue to betreated such that current can flow from the active electrode to thereturn electrode through the tissue. Accordingly, the electrosurgical/RFmodule 23 generator may be configured for therapeutic purposes byapplying electrical energy to the tissue T sufficient for treating thetissue (e.g., cauterization). For example, in some aspects, the activeand/or return electrode may be positioned on the jaw assembly describedherein.

In one aspect, the electrosurgical/RF generator module 23 may beconfigured to deliver a subtherapeutic RF signal to implement a tissueimpedance measurement module. In one aspect, the electrosurgical/RFgenerator module 23 comprises a bipolar radio frequency generator. Inone aspect, the electrosurgical/RF generator module 23 may be configuredto monitor electrical impedance Z, of tissue T and to control thecharacteristics of time and power level based on the tissue T by way ofa return electrode provided on a clamp member of the end effectorassembly 26. Accordingly, the electrosurgical/RF generator module 23 maybe configured for subtherapeutic purposes for measuring the impedance orother electrical characteristics of the tissue T. Techniques and circuitconfigurations for measuring the impedance or other electricalcharacteristics of tissue Tare discussed in more detail in commonlyassigned U.S. Patent Publication No. 2011/0015631, titled“Electrosurgical Generator for Ultrasonic Surgical Instrument,” thedisclosure of which is herein incorporated by reference in its entirety.

A suitable ultrasonic generator module 21 may be configured tofunctionally operate in a manner similar to the GEN300 sold by EthiconEndo-Surgery, Inc. of Cincinnati, Ohio as is disclosed in one or more ofthe following U.S. patents, all of which are incorporated by referenceherein: U.S. Pat. No. 6,480,796 (Method for Improving the Start Up of anUltrasonic System Under Zero Load Conditions); U.S. Pat. No. 6,537,291(Method for Detecting a Loose Blade in a Hand Piece Connected to anUltrasonic Surgical System); U.S. Pat. No. 6,662,127 (Method forDetecting Presence of a Blade in an Ultrasonic System); U.S. Pat. No.6,977,495 (Detection Circuitry for Surgical Handpiece System); U.S. Pat.No. 7,077,853 (Method for Calculating Transducer Capacitance toDetermine Transducer Temperature); U.S. Pat. No. 7,179,271 (Method forDriving an Ultrasonic System to Improve Acquisition of Ultrasonic BladeResonance Frequency at Startup); and U.S. Pat. No. 7,273,483 (Apparatusand Method for Alerting Generator Function in an Ultrasonic SurgicalSystem).

It will be appreciated that in various aspects, the generator 20 may beconfigured to operate in several modes. In one mode, the generator 20may be configured such that the ultrasonic generator module 21 and theelectrosurgical/RF generator module 23 may be operated independently.

For example, the ultrasonic generator module 21 may be activated toapply ultrasonic energy to the end effector assembly 26 andsubsequently, either therapeutic sub-therapeutic RF energy may beapplied to the end effector assembly 26 by the electrosurgical/RFgenerator module 23. As previously discussed, the sub-therapeuticelectrosurgical/RF energy may be applied to tissue clamped between claimelements of the end effector assembly 26 to measure tissue impedance tocontrol the activation, or modify the activation, of the ultrasonicgenerator module 21. Tissue impedance feedback from the application ofthe sub-therapeutic energy also may be employed to activate atherapeutic level of the electrosurgical/RF generator module 23 to sealthe tissue (e.g., vessel) clamped between claim elements of the endeffector assembly 26.

In another aspect, the ultrasonic generator module 21 and theelectrosurgical/RF generator module 23 may be activated simultaneously.In one example, the ultrasonic generator module 21 is simultaneouslyactivated with a sub-therapeutic RF energy level to measure tissueimpedance simultaneously while the ultrasonic blade of the end effectorassembly 26 cuts and coagulates the tissue (or vessel) clamped betweenthe clamp elements of the end effector assembly 26. Such feedback may beemployed, for example, to modify the drive output of the ultrasonicgenerator module 21. In another example, the ultrasonic generator module21 may be driven simultaneously with electrosurgical/RF generator module23 such that the ultrasonic blade portion of the end effector assembly26 is employed for cutting the damaged tissue while theelectrosurgical/RF energy is applied to electrode portions of the endeffector clamp assembly 26 for sealing the tissue (or vessel).

When the generator 20 is activated via the triggering mechanism,electrical energy is continuously applied by the generator 20 to atransducer stack or assembly of the acoustic assembly. In anotheraspect, electrical energy is intermittently applied (e.g., pulsed) bythe generator 20. A phaselocked loop in the control system of thegenerator 20 may monitor feedback from the acoustic assembly. The phaselock loop adjusts the frequency of the electrical energy sent by thegenerator 20 to match the resonant frequency of the selectedlongitudinal mode of vibration of the acoustic assembly. In addition, asecond feedback loop in the control system 25 maintains the electricalcurrent supplied to the acoustic assembly at a pre-selected constantlevel in order to achieve substantially constant excursion at the endeffector 18 of the acoustic assembly. In yet another aspect, a thirdfeedback loop in the control system 25 monitors impedance betweenelectrodes located in the end effector assembly 26. Although FIGS. 1-5show a manually operated ultrasonic surgical instrument, it will beappreciated that ultrasonic surgical instruments may also be used inrobotic applications, for example, as described herein as well ascombinations of manual and robotic applications.

In ultrasonic operation mode, the electrical signal supplied to theacoustic assembly may cause the distal end of the end effector 18, tovibrate longitudinally in the range of, for example, approximately 20kHz to 250 kHz. According to various aspects, the ultrasonic blade 22may vibrate in the range of about 54 kHz to 56 kHz, for example, atabout 55.5 kHz. In other aspects, the ultrasonic blade 22 may vibrate atother frequencies including, for example, about 31 kHz or about 80 kHz.The excursion of the vibrations at the ultrasonic blade can becontrolled by, for example, controlling the amplitude of the electricalsignal applied to the transducer assembly of the acoustic assembly bythe generator 20. As noted above, the triggering mechanism of thegenerator 20 allows a user to activate the generator 20 so thatelectrical energy may be continuously or intermittently supplied to theacoustic assembly. The generator 20 also has a power line for insertionin an electro-surgical unit or conventional electrical outlet. It iscontemplated that the generator 20 can also be powered by a directcurrent (DC) source, such as a battery. The generator 20 can compriseany suitable generator, such as Model No. GEN04, and/or Model No. GEN11available from Ethicon Endo-Surgery, Inc.

FIG. 2 is a left perspective view of one example aspect of theultrasonic surgical instrument 10 showing the handle assembly 12, thedistal rotation assembly 13, and the elongated shaft assembly 14. FIG. 3shows the end effector assembly 26. In the illustrated aspect theelongated shaft assembly 14 comprises a distal end 52 dimensioned tomechanically engage the end effector assembly 26 and a proximal end 50that mechanically engages the handle assembly 12 and the distal rotationassembly 13. The proximal end 50 of the elongated shaft assembly 14 isreceived within the handle assembly 12 and the distal rotation assembly13. More details relating to the connections between the elongated shaftassembly 14, the handle assembly 12, and the distal rotation assembly 13are provided in the description of FIG. 5. In the illustrated aspect,the trigger assembly 24 comprises a trigger 32 that operates inconjunction with a fixed handle 34. The fixed handle 34 and the trigger32 are ergonomically formed and adapted to interface comfortably withthe user. The fixed handle 34 is integrally associated with the handleassembly 12. The trigger 32 is pivotally movable relative to the fixedhandle 34 as explained in more detail below with respect to theoperation of the ultrasonic surgical instrument 10. The trigger 32 ispivotally movable in direction 33 a toward the fixed handle 34 when theuser applies a squeezing force against the trigger 32. A spring element98 (FIG. 5) causes the trigger 32 to pivotally move in direction 33 bwhen the user releases the squeezing force against the trigger 32.

In one example aspect, the trigger 32 comprises an elongated triggerhook 36, which defines an aperture 38 between the elongated trigger hook36 and the trigger 32. The aperture 38 is suitably sized to receive oneor multiple fingers of the user therethrough. The trigger 32 also maycomprise a resilient portion 32 a molded over the trigger 32 substrate.The overmolded resilient portion 32 a is formed to provide a morecomfortable contact surface for control of the trigger 32 in outwarddirection 33 b. In one example aspect, the overmolded resilient portion32 a may be provided over a portion of the elongated trigger hook 36.The proximal surface of the elongated trigger hook 32 remains uncoatedor coated with a non-resilient substrate to enable the user to easilyslide their fingers in and out of the aperture 38. In another aspect,the geometry of the trigger forms a fully closed loop which defines anaperture suitably sized to receive one or multiple fingers of the usertherethrough. The fully closed loop trigger also may comprise aresilient portion molded over the trigger substrate.

In one example aspect, the fixed handle 34 comprises a proximal contactsurface 40 and a grip anchor or saddle surface 42. The saddle surface 42rests on the web where the thumb and the index finger are joined on thehand. The proximal contact surface 40 has a pistol grip contour thatreceives the palm of the hand in a normal pistol grip with no rings orapertures. The profile curve of the proximal contact surface 40 may becontoured to accommodate or receive the palm of the hand. Astabilization tail 44 is located towards a more proximal portion of thehandle assembly 12. The stabilization tail 44 may be in contact with theuppermost web portion of the hand located between the thumb and theindex finger to stabilize the handle assembly 12 and make the handleassembly 12 more controllable.

In one example aspect, the switch assembly 28 may comprise a toggleswitch 30. The toggle switch 30 may be implemented as a single componentwith a central pivot 304 located within inside the handle assembly 12 toeliminate the possibility of simultaneous activation. In one exampleaspect, the toggle switch 30 comprises a first projecting knob 30 a anda second projecting knob 30 b to set the power setting of the ultrasonictransducer 16 between a minimum power level (e.g., MIN) and a maximumpower level (e.g., MAX). In another aspect, the rocker switch may pivotbetween a standard setting and a special setting. The special settingmay allow one or more special programs, processes, or algorithms anddescribed herein to be implemented by the device. The toggle switch 30rotates about the central pivot as the first projecting knob 30 a andthe second projecting knob 30 b are actuated The one or more projectingknobs 30 a, 30 b are coupled to one or more arms that move through asmall arc and cause electrical contacts to close or open an electriccircuit to electrically energize or de-energize the ultrasonictransducer 16 in accordance with the activation of the first or secondprojecting knobs 30 a, 30 b. The toggle switch 30 is coupled to thegenerator 20 to control the activation of the ultrasonic transducer 16.The toggle switch 30 comprises one or more electrical power settingswitches to activate the ultrasonic transducer 16 to set one or morepower settings for the ultrasonic transducer 16. The forces required toactivate the toggle switch 30 are directed substantially toward thesaddle point 42, thus avoiding any tendency of the instrument to rotatein the hand when the toggle switch 30 is activated.

In one example aspect, the first and second projecting knobs 30 a, 30 bare located on the distal end of the handle assembly 12 such that theycan be easily accessible by the user to activate the power with minimal,or substantially no, repositioning of the hand grip, making it suitableto maintain control and keep attention focused on the surgical site(e.g., a monitor in a laparoscopic procedure) while activating thetoggle switch 30. The projecting knobs 30 a, 30 b may be configured towrap around the side of the handle assembly 12 to some extent to be moreeasily accessible by variable finger lengths and to allow greaterfreedom of access to activation in awkward positions or for shorterfingers. In the illustrated aspect, the first projecting knob 30 acomprises a plurality of tactile elements 30 c, e.g., texturedprojections or “bumps” in the illustrated aspect, to allow the user todifferentiate the first projecting knob 30 a from the second projectingknob 30 b. It will be appreciated by those skilled in the art thatseveral ergonomic features may be incorporated into the handle assembly12. Such ergonomic features are described in U.S. Pat. App. Pub. No.2009/0105750 entitled “Ergonomic Surgical Instruments” which isincorporated by reference herein in its entirety.

In one example aspect, the toggle switch 30 may be operated by the handof the user. The user may easily access the first and second projectingknobs 30 a, 30 b at any point while also avoiding inadvertent orunintentional activation at any time. The toggle switch 30 may readilyoperated with a finger to control the power to the ultrasonic assembly16 and/or to the ultrasonic assembly 16. For example, the index fingermay be employed to activate the first contact portion 30 a to tum on theultrasonic assembly 16 to a maximum (MAX) power level. The index fingermay be employed to activate the second contact portion 30 b to tum onthe ultrasonic assembly 16 to a minimum (MIN) power level. In anotheraspect, the rocker switch may pivot the instrument 10 between a standardsetting and a special setting. The special setting may allow one or morespecial programs to be implemented by the instrument 10. The toggleswitch 30 may be operated without the user having to look at the firstor second projecting knob 30 a, 30 b. For example, the first projectingknob 30 a or the second projecting knob 30 b may comprise a texture orprojections to tactilely differentiate between the first and secondprojecting knobs 30 a, 30 b without looking.

In one example aspect, the distal rotation assembly 13 is rotatablewithout limitation in either direction about a longitudinal axis “T.”The distal rotation assembly 13 is mechanically engaged to the elongatedshaft assembly 14. The distal rotation assembly 13 is located on adistal end of the handle assembly 12. The distal rotation assembly 13comprises a cylindrical hub 46 and a rotation knob 48 formed over thehub 46. The hub 46 mechanically engages the elongated shaft assembly 14.The rotation knob 48 may comprise fluted polymeric features and may beengaged by a finger (e.g., an index finger) to rotate the elongatedshaft assembly 14. The hub 46 may comprise a material molded over theprimary structure to form the rotation knob 48. The rotation knob 48 maybe overmolded over the hub 46. The hub 46 comprises an end cap portion46 a that is exposed at the distal end. The end cap portion 46 a of thehub 46 may contact the surface of a trocar during laparoscopicprocedures. The hub 46 may be formed of a hard durable plastic such aspolycarbonate to alleviate any friction that may occur between the endcap portion 46 a and the trocar. The rotation knob 48 may comprise“scallops” or flutes formed of raised ribs 48 a and concave portions 48b located between the ribs 48 a to provide a more precise rotationalgrip. In one example aspect, the rotation knob 48 may comprise aplurality of flutes (e.g., three or more flutes). In other aspects, anysuitable number of flutes may be employed. The rotation knob 48 may beformed of a softer polymeric material overmolded onto the hard plasticmaterial. For example, the rotation knob 48 may be formed of pliable,resilient, flexible polymeric materials including Versaflex® TPE alloysmade by GLS Corporation, for example. This softer overmolded materialmay provide a greater grip and more precise control of the movement ofthe rotation knob 48. It will be appreciated that any materials thatprovide adequate resistance to sterilization, are biocompatible, andprovide adequate frictional resistance to surgical gloves may beemployed to form the rotation knob 48.

In one example aspect, the handle assembly 12 is formed from two (2)housing portions or shrouds comprising a first portion 12 a and a secondportion 12 b. From the perspective of a user viewing the handle assembly12 from the distal end towards the proximal end, the first portion 12 ais considered the right portion and the second portion 12 b isconsidered the left portion. Each of the first and second portions 12 a,12 b includes a plurality of interfaces 69 (FIG. 5) dimensioned tomechanically align and engage each another to form the handle assembly12 and enclosing the internal working components thereof. The fixedhandle 34, which is integrally associated with the handle assembly 12,takes shape upon the assembly of the first and second portions 12 a and12 b of the handle assembly 12. A plurality of additional interfaces(not shown) may be disposed at various points around the periphery ofthe first and second portions 12 a and 12 b of the handle assembly 12for ultrasonic welding purposes, e.g., energy direction/deflectionpoints. The first and second portions 12 a and 12 b (as well as theother components described below) may be assembled together in anyfashion known in the art. For example, alignment pins, snap-likeinterfaces, tongue and groove interfaces, locking tabs, adhesive ports,may all be utilized either alone or in combination for assemblypurposes.

In one example aspect, the elongated shaft assembly 14 comprises aproximal end 50 adapted to mechanically engage the handle assembly 12and the distal rotation assembly 13; and a distal end 52 adapted tomechanically engage the end effector assembly 26. The elongated shaftassembly 14 comprises an outer tubular sheath 56 and a reciprocatingtubular actuating member 58 located within the outer tubular sheath 56.The proximal end of the tubular reciprocating tubular actuating member58 is mechanically engaged to the trigger 32 of the handle assembly 12to move in either direction 60A or 60B in response to the actuationand/or release of the trigger 32. The pivotably moveable trigger 32 maygenerate reciprocating motion along the longitudinal axis “T.” Suchmotion may be used, for example, to actuate the jaws or clampingmechanism of the end effector assembly 26. A series of linkagestranslate the pivotal rotation of the trigger 32 to axial movement of ayoke coupled to an actuation mechanism, which controls the opening andclosing of the jaws of the clamping mechanism of the end effectorassembly 26. The distal end of the tubular reciprocating tubularactuating member 58 is mechanically engaged to the end effector assembly26. In the illustrated aspect, the distal end of the tubularreciprocating tubular actuating member 58 is mechanically engaged to aclamp arm assembly 64, which is pivotable about a pivot point 70 (FIG.4), to open and close the clamp arm assembly 64 in response to theactuation and/or release of the trigger 32. For example, in theillustrated aspect, the clamp arm assembly 64 is movable in direction62A from an open position to a closed position about a pivot point 70when the trigger 32 is squeezed in direction 33 a. The clamp armassembly 64 is movable in direction 62B from a closed position to anopen position about the pivot point 70 when the trigger 32 is releasedor outwardly contacted in direction 33 b.

In one example aspect, the end effector assembly 26 is attached at thedistal end 52 of the elongated shaft assembly 14 and includes a clamparm assembly 64 and a ultrasonic blade 66. The jaws of the clampingmechanism of the end effector assembly 26 are formed by clamp armassembly 64 and the ultrasonic blade 66. The ultrasonic blade 66 isultrasonically actuatable and is acoustically coupled to the ultrasonictransducer 16. The trigger 32 on the handle assembly 12 is ultimatelyconnected to a drive assembly, which together, mechanically cooperate toeffect movement of the clamp arm assembly 64. Squeezing the trigger 32in direction 33 a moves the clamp arm assembly 64 in direction 62A froman open position, wherein the clamp arm assembly 64 and the ultrasonicblade 66 are disposed in a spaced relation relative to one another, to aclamped or closed position, wherein the clamp arm assembly 64 and theultrasonic blade 66 cooperate to grasp tissue therebetween. The clamparm assembly 64 may comprise a clamp pad 69 to engage tissue between theultrasonic blade 66 and the clamp arm 64. Releasing the trigger 32 indirection 33 b moves the clamp arm assembly 64 in direction 62B from aclosed relationship, to an open position, wherein the clamp arm assembly64 and the ultrasonic blade 66 are disposed in a spaced relationrelative to one another.

The proximal portion of the handle assembly 12 comprises a proximalopening 68 to receive the distal end of the ultrasonic assembly 16. Theultrasonic assembly 16 is inserted in the proximal opening 68 and ismechanically engaged to the elongated shaft assembly 14.

In one example aspect, the elongated trigger hook 36 portion of thetrigger 32 provides a longer trigger lever with a shorter span androtation travel. The longer lever of the elongated trigger hook 36allows the user to employ multiple fingers within the aperture 38 tooperate the elongated trigger hook 36 and cause the trigger 32 to pivotin direction 33 b to open the jaws of the end effector assembly 26. Forexample, the user may insert three fingers (e.g., the middle, ring, andlittle fingers) in the aperture 38. Multiple fingers allows the surgeonto exert higher input forces on the trigger 32 and the elongated triggerhook 326 to activate the end effector assembly 26. The shorter span androtation travel creates a more comfortable grip when closing orsqueezing the trigger 32 in direction 33 a or when opening the trigger32 in the outward opening motion in direction 33 b lessening the need toextend the fingers further outward. This substantially lessens handfatigue and strain associated with the outward opening motion of thetrigger 32 in direction 33 b. The outward opening motion of the triggermay be spring-assisted by spring element 98 (FIG. 5) to help alleviatefatigue. The opening spring force is sufficient to assist the ease ofopening, but not strong enough to adversely impact the tactile feedbackof tissue tension during spreading dissection.

For example, during a surgical procedure either the index finger may beused to control the rotation of the elongated shaft assembly 14 tolocate the jaws of the end effector assembly 26 in a suitableorientation. The middle and/or the other lower fingers may be used tosqueeze the trigger 32 and grasp tissue within the jaws. Once the jawsare located in the desired position and the jaws are clamped against thetissue, the index finger can be used to activate the toggle switch 30 toadjust the power level of the ultrasonic transducer 16 to treat thetissue. Once the tissue has been treated, the user the may release thetrigger 32 by pushing outwardly in the distal direction against theelongated trigger hook 36 with the middle and/or lower fingers to openthe jaws of the end effector assembly 26. This basic procedure may beperformed without the user having to adjust their grip of the handleassembly 12.

FIGS. 3-4 illustrate the connection of the elongated shaft assembly 14relative to the end effector assembly 26. As previously described, inthe illustrated aspect, the end effector assembly 26 comprises a clamparm assembly 64 and a ultrasonic blade 66 to form the jaws of theclamping mechanism. The ultrasonic blade 66 may be an ultrasonicallyactuatable ultrasonic blade acoustically coupled to the ultrasonictransducer 16. The trigger 32 is mechanically connected to a driveassembly. Together, the trigger 32 and the drive assembly mechanicallycooperate to move the clamp arm assembly 64 to an open position indirection 62A wherein the clamp arm assembly 64 and the ultrasonic blade66 are disposed in spaced relation relative to one another, to a clampedor closed position in direction 62B wherein the clamp arm assembly 64and the ultrasonic blade 66 cooperate to grasp tissue therebetween. Theclamp arm assembly 64 may comprise a clamp pad 69 to engage tissuebetween the ultrasonic blade 66 and the clamp arm 64. The distal end ofthe tubular reciprocating tubular actuating member 58 is mechanicallyengaged to the end effector assembly 26. In the illustrated aspect, thedistal end of the tubular reciprocating tubular actuating member 58 ismechanically engaged to the clamp arm assembly 64, which is pivotableabout the pivot point 70, to open and close the clamp arm assembly 64 inresponse to the actuation and/or release of the trigger 32. For example,in the illustrated aspect, the clamp arm assembly 64 is movable from anopen position to a closed position in direction 62B about a pivot point70 when the trigger 32 is squeezed in direction 33 a. The clamp armassembly 64 is movable from a closed position to an open position indirection 62A about the pivot point 70 when the trigger 32 is releasedor outwardly contacted in direction 33 b.

As previously discussed, the clamp arm assembly 64 may compriseelectrodes electrically coupled to the electrosurgical/RF generatormodule 23 to receive therapeutic and/or sub-therapeutic energy, wherethe electrosurgical/RF energy may be applied to the electrodes eithersimultaneously or non simultaneously with the ultrasonic energy beingapplied to the ultrasonic blade 66. Such energy activations may beapplied in any suitable combinations to achieve a desired tissue effectin cooperation with an algorithm or other control logic.

FIG. 5 is an exploded view of the ultrasonic surgical instrument 10shown in FIG. 2. In the illustrated aspect, the exploded view shows theinternal elements of the handle assembly 12, the handle assembly 12, thedistal rotation assembly 13, the switch assembly 28, and the elongatedshaft assembly 14. In the illustrated aspect, the first and secondportions 12 a, 12 b mate to form the handle assembly 12. The first andsecond portions 12 a, 12 b each comprises a plurality of interfaces 69dimensioned to mechanically align and engage one another to form thehandle assembly 12 and enclose the internal working components of theultrasonic surgical instrument 10. The rotation knob 48 is mechanicallyengaged to the outer tubular sheath 56 so that it may be rotated incircular direction 54 up to 360°. The outer tubular sheath 56 is locatedover the reciprocating tubular actuating member 58, which ismechanically engaged to and retained within the handle assembly 12 via aplurality of coupling elements 72. The coupling elements 72 may comprisean 0-ring 72 a, a tube collar cap 72 b, a distal washer 72 c, a proximalwasher 72 d, and a thread tube collar 72 e. The reciprocating tubularactuating member 58 is located within a reciprocating yoke 84, which isretained between the first and second portions 12 a, 12 b of the handleassembly 12. The yoke 84 is part of a reciprocating yoke assembly 88. Aseries of linkages translate the pivotal rotation of the elongatedtrigger hook 32 to the axial movement of the reciprocating yoke 84,which controls the opening and closing of the jaws of the clampingmechanism of the end effector assembly 26 at the distal end of theultrasonic surgical instrument 10. In one example aspect, a four-linkdesign provides mechanical advantage in a relatively short rotationspan, for example.

In one example aspect, an ultrasonic transmission waveguide 78 isdisposed inside the reciprocating tubular actuating member 58. Thedistal end 52 of the ultrasonic transmission waveguide 78 isacoustically coupled (e.g., directly or indirectly mechanically coupled)to the ultrasonic blade 66 and the proximal end 50 of the ultrasonictransmission waveguide 78 is received within the handle assembly 12. Theproximal end 50 of the ultrasonic transmission waveguide 78 is adaptedto acoustically couple to the distal end of the ultrasonic transducer16. The ultrasonic transmission waveguide 78 is isolated from the otherelements of the elongated shaft assembly 14 by a protective sheath 80and a plurality of isolation elements 82, such as silicone rings. Theouter tubular sheath 56, the reciprocating tubular actuating member 58,and the ultrasonic transmission waveguide 78 are mechanically engaged bya pin 74. The switch assembly 28 comprises the toggle switch 30 andelectrical elements 86 a,b to electrically energize the ultrasonictransducer 16 in accordance with the activation of the first or secondprojecting knobs 30 a, 30 b.

In one example aspect, the outer tubular sheath 56 isolates the user orthe patient from the ultrasonic vibrations of the ultrasonictransmission waveguide 78. The outer tubular sheath 56 generallyincludes a hub 76. The outer tubular sheath 56 is threaded onto thedistal end of the handle assembly 12. The ultrasonic transmissionwaveguide 78 extends through the opening of the outer tubular sheath 56and the isolation elements 82 isolate the ultrasonic transmissionwaveguide 24 from the outer tubular sheath 56. The outer tubular sheath56 may be attached to the waveguide 78 with the pin 74. The hole toreceive the pin 74 in the waveguide 78 may occur nominally at adisplacement node. The waveguide 78 may screw or snap into the handpiece handle assembly 12 by a stud. Flat portions on the hub 76 mayallow the assembly to be torqued to a required level. In one exampleaspect, the hub 76 portion of the outer tubular sheath 56 is preferablyconstructed from plastic and the tubular elongated portion of the outertubular sheath 56 is fabricated from stainless steel. Alternatively, theultrasonic transmission waveguide 78 may comprise polymeric materialsurrounding it to isolate it from outside contact.

In one example aspect, the distal end of the ultrasonic transmissionwaveguide 78 may be coupled to the proximal end of the ultrasonic blade66 by an internal threaded connection, preferably at or near anantinode. It is contemplated that the ultrasonic blade 66 may beattached to the ultrasonic transmission waveguide 78 by any suitablemeans, such as a welded joint or the like. Although the ultrasonic blade66 may be detachable from the ultrasonic transmission waveguide 78, itis also contemplated that the single element end effector (e.g., theultrasonic blade 66) and the ultrasonic transmission waveguide 78 may beformed as a single unitary piece.

In one example aspect, the trigger 32 is coupled to a linkage mechanismto translate the rotational motion of the trigger 32 in directions 33 aand 33 b to the linear motion of the reciprocating tubular actuatingmember 58 in corresponding directions 60 a and 60 b (FIG. 2). Thetrigger 32 comprises a first set of flanges 98 with openings formedtherein to receive a first yoke pin 94 a. The first yoke pin 94 a isalso located through a set of openings formed at the distal end of theyoke 84. The trigger 32 also comprises a second set of flanges 96 toreceive a first end of a link 92. A trigger pin 90 is received inopenings formed in the link 92 and the second set of flanges 96. Thetrigger pin 90 is received in the openings formed in the link 92 and thesecond set of flanges 96 and is adapted to couple to the first andsecond portions 12 a, 12 b of the handle assembly 12 to form a triggerpivot point for the trigger 32. A second end of the link 92 is receivedin a slot formed in a proximal end of the yoke 84 and is retainedtherein by a second yoke pin 94 b. As the trigger 32 is pivotallyrotated about a pivot point formed by the trigger pin 90, the yoketranslates horizontally along a longitudinal axis “T” in a directionindicated by arrows 60 a,b.

FIG. 6 illustrates a diagram of one aspect of a force feedback surgicaldevice 100 which may include or implement many of the features describedherein. For example, in one aspect, surgical device 100 may be similarto or representative of surgical instrument 10. The surgical device 100may include a generator 102. The surgical device 100 may also include anultrasonic end effector 106, which may be activated when a clinicianoperates a trigger 110. When the trigger 110 is actuated, a force sensor112 may generate a signal indicating the amount of force being appliedto the trigger 110. In addition to, or instead of force sensor 112, thedevice 100 may include a position sensor 113, which may generate asignal indicating the position of the trigger 110 (e.g., how far thetrigger has been depressed or otherwise actuated). In one aspect, theposition sensor 113 may be a sensor positioned with the outer tubularsheath 56 described above or reciprocating tubular actuating member 58located within the outer tubular sheath 56 described above In oneaspect, the sensor may be a Hall-effect sensor or any suitabletransducer that varies its output voltage in response to a magneticfield. The Hall effect sensor may be used for proximity switching,positioning, speed detection, and current sensing applications. In oneaspect, the Hall-effect sensor operates as an analog transducer,directly returning a voltage. With a known magnetic field, its distancefrom the Hall plate can be determined.

A control circuit 108 may receive the signals from the sensors 112and/or 113. The control circuit 108 may include any suitable analog ordigital circuit components. The control circuit 108 also may communicatewith the generator 102 and/or the transducer 104 to modulate the powerdelivered to the end effector 106 and/or the generator level orultrasonic blade amplitude of the end effector 106 based on the forceapplied to the trigger 110 and/or the position of the trigger 110 and/orthe position of the outer tubular sheath 56 described above relative tothe reciprocating tubular actuating member 58 located within the outertubular sheath 56 described above (e.g., as measured by a Hall-effectsensor and magnet combination). For example, as more force is applied tothe trigger 110, more power and/or a higher ultrasonic blade amplitudemay be delivered to the end effector 106. According to various aspects,the force sensor 112 may be replaced by a multi-position switch.

According to various aspects, the end effector 106 may include a clampor clamping mechanism, for example, such as that described above withrespect to FIGS. 1-5. When the trigger 110 is initially actuated, theclamping mechanism may close, clamping tissue between a clamp arm andthe end effector 106. As the force applied to the trigger increases(e.g., as sensed by force sensor 112) the control circuit 608 mayincrease the power delivered to the end effector 106 by the transducer104 and/or the generator level or ultrasonic blade amplitude broughtabout in the end effector 106. In one aspect, trigger position, assensed by position sensor 113 or clamp or clamp arm position, as sensedby position sensor 113 (e.g., with a Hall-effect sensor), may be used bythe control circuit 108 to set the power and/or amplitude of the endeffector 106. For example, as the trigger is moved further towards afully actuated position, or the clamp or clamp arm moves further towardsthe ultrasonic blade (or end effector 106), the power and/or amplitudeof the end effector 106 may be increased.

According to various aspects, the surgical device 100 also may includeone or more feedback devices for indicating the amount of powerdelivered to the end effector 106. For example, a speaker 114 may emit asignal indicative of the end effector power. According to variousaspects, the speaker 114 may emit a series of pulse sounds, where thefrequency of the sounds indicates power. In addition to, or instead ofthe speaker 114, the device may include a visual display 116. The visualdisplay 116 may indicate end effector power according to any suitablemethod. For example, the visual display 116 may include a series oflight emitting diodes (LEDs), where end effector power is indicated bythe number of illuminated LEDs. The speaker 114 and/or visual display116 may be driven by the control circuit 108. According to variousaspects, the device 100 may include a ratcheting device (not shown)connected to the trigger 110. The ratcheting device may generate anaudible sound as more force is applied to the trigger 110, providing anindirect indication of end effector power. The device 100 may includeother features that may enhance safety. For example, the control circuit108 may be configured to prevent power from being delivered to the endeffector 106 in excess of a predetermined threshold. Also, the controlcircuit 108 may implement a delay between the time when a change in endeffector power is indicated (e.g., by speaker 114 or display 116), andthe time when the change in end effector power is delivered. In thisway, a clinician may have ample warning that the level of ultrasonicpower that is to be delivered to the end effector 106 is about tochange.

FIG. 7 is a simplified diagram of one aspect of the generator 102 whichmay provide for inductorless tuning, among other benefits. FIGS. 8A-8Cillustrate an architecture of the generator 102 of FIG. 7 according toone aspect of the present disclosure. FIG. 9 illustrates a controller196 for monitoring input devices and controlling output devices inaccordance with one aspect of the present disclosure. With reference nowto FIGS. 7-9, the generator 102 may comprise a patient isolated stage152 in communication with a non-isolated stage 154 via a powertransformer 156. A secondary winding 158 of the power transformer 156 iscontained in the isolated stage 152 and may comprise a tappedconfiguration (e.g., a center-tapped or non-center tapped configuration)to define drive signal outputs 160 a, 160 b, 160 c for outputting drivesignals to different surgical devices, such as, for example, a surgicaldevice 100, ultrasonic surgical instrument 10, or an electrosurgicaldevice. In particular, drive signal outputs 160 a, 160 c may output adrive signal (e.g., a 420V RMS drive signal) to an ultrasonic instrument10, and drive signal outputs 160 b, 160 c may output a drive signal(e.g., a 100V RMS drive signal) to an electro surgical device, withoutput 160 b corresponding to the center tap of the power transformer156. The non-isolated stage 154 may comprise a power amplifier 162having an output connected to a primary winding 164 of the powertransformer 156. In certain aspects the power amplifier 162 may comprisea push-pull amplifier, for example. The non-isolated stage 154 mayfurther comprise a programmable logic device 166 for supplying a digitaloutput to a digital-to-analog converter (DAC) 168, which in tum suppliesa corresponding analog signal to an input of the power amplifier 162. Incertain aspects the programmable logic device 166 may comprise afield-programmable gate array (FPGA), for example. The programmablelogic device 166, by virtue of controlling the power amplifier's 162input via the DAC 168, may therefore control any of a number ofparameters (e.g., frequency, waveform shape, waveform amplitude) ofdrive signals appearing at the drive signal outputs 160 a, 160 b, 160 c.In certain aspects and as discussed below, the programmable logic device166, in conjunction with a processor (e.g., processor 174 discussedbelow), may implement a number of digital signal processing (DSP)-basedand/or other control algorithms to control parameters of the drivesignals output by the generator 102.

Power may be supplied to a power rail of the power amplifier 162 by aswitch-mode regulator 170. In certain aspects the switch-mode regulator170 may comprise an adjustable buck regulator, for example. Thenon-isolated stage 154 may further comprise a processor 174, which inone aspect may comprise a DSP processor such as an Analog DevicesADSP-21469 SHARC DSP, available from Analog Devices, Norwood, Mass., forexample. In certain aspects the processor 174 may control operation ofthe switch-mode power converter 170 responsive to voltage feedback datareceived from the power amplifier 162 by the processor 174 via ananalog-to-digital converter (ADC) 176. In one aspect, for example, theprocessor 174 may receive as input, via the ADC 176, the waveformenvelope of a signal (e.g., an RF signal) being amplified by the poweramplifier 162. The processor 174 may then control the switch-moderegulator 170 (e.g., via a pulse-width modulated (PWM) output) such thatthe rail voltage supplied to the power amplifier 162 tracks the waveformenvelope of the amplified signal. By dynamically modulating the railvoltage of the power amplifier 162 based on the waveform envelope, theefficiency of the power amplifier 162 may be significantly improvedrelative to a fixed rail voltage amplifier schemes.

In certain aspects and as discussed in further detail in connection withFIGS. 10A and 10B, the programmable logic device 166, in conjunctionwith the processor 174, may implement a direct digital synthesizer (DDS)control scheme to control the waveform shape, frequency and/or amplitudeof drive signals output by the generator 102. In one aspect, forexample, the programmable logic device 166 may implement a DDS controlalgorithm 268 by recalling waveform samples stored in adynamically-updated lookup table (LUT), such as a RAM LUT which may beembedded in an FPGA. This control algorithm is particularly useful forultrasonic applications in which an ultrasonic transducer may be drivenby a clean sinusoidal current at its resonant frequency. Because otherfrequencies may excite parasitic resonances, minimizing or reducing thetotal distortion of the motional branch current may correspondinglyminimize or reduce undesirable resonance effects. Because the waveformshape of a drive signal output by the generator 102 is impacted byvarious sources of distortion present in the output drive circuit (e.g.,the power transformer 156, the power amplifier 162), voltage and currentfeedback data based on the drive signal may be input into an algorithm,such as an error control algorithm implemented by the processor 174,which compensates for distortion by suitably pre-distorting or modifyingthe waveform samples stored in the LUT on a dynamic, ongoing basis(e.g., in real-time). In one aspect, the amount or degree ofpre-distortion applied to the LUT samples may be based on the errorbetween a computed motional branch current and a desired currentwaveform shape, with the error being determined on a sample-by samplebasis. In this way, the predistorted LUT samples, when processed throughthe drive circuit, may result in a motional branch drive signal havingthe desired waveform shape (e.g., sinusoidal) for optimally driving theultrasonic transducer. In such aspects, the LUT waveform samples willtherefore not represent the desired waveform shape of the drive signal,but rather the waveform shape that is required to ultimately produce thedesired waveform shape of the motional branch drive signal whendistortion effects are taken into account.

The non-isolated stage 154 may further comprise an ADC 178 and an ADC180 coupled to the output of the power transformer 156 via respectiveisolation transformers 182, 184 for respectively sampling the voltageand current of drive signals output by the generator 102. In certainaspects, the ADCs 178, 180 may be configured to sample at high speeds(e.g., 80 Msps) to enable oversampling of the drive signals. In oneaspect, for example, the sampling speed of the ADCs 178, 180 may enableapproximately 200× (depending on drive frequency) oversampling of thedrive signals. In certain aspects, the sampling operations of the ADCs178, 180 may be performed by a single ADC receiving input voltage andcurrent signals via a two-way multiplexer. The use of high-speedsampling in aspects of the generator 102 may enable, among other things,calculation of the complex current flowing through the motional branch(which may be used in certain aspects to implement DDS based waveformshape control described above), accurate digital filtering of thesampled signals, and calculation of real power consumption with a highdegree of precision. Voltage and current feedback data output by theADCs 178, 180 may be received and processed (e.g., FIFO buffering,multiplexing) by the programmable logic device 166 and stored in datamemory for subsequent retrieval by, for example, the processor 174. Asnoted above, voltage and current feedback data may be used as input toan algorithm for pre-distorting or modifying LUT waveform samples on adynamic and ongoing basis. In certain aspects, this may require eachstored voltage and current feedback data pair to be indexed based on, orotherwise associated with, a corresponding LUT sample that was output bythe programmable logic device 166 when the voltage and current feedbackdata pair was acquired. Synchronization of the LUT samples and thevoltage and current feedback data in this manner contributes to thecorrect timing and stability of the pre-distortion algorithm.

In certain aspects, the voltage and current feedback data may be used tocontrol the frequency and/or amplitude (e.g., current amplitude) of thedrive signals. In one aspect, for example, voltage and current feedbackdata may be used to determine impedance phase. The frequency of thedrive signal may then be controlled to minimize or reduce the differencebetween the determined impedance phase and an impedance phase setpoint(e.g., 0°), thereby minimizing or reducing the effects of ultrasonicdistortion and correspondingly enhancing impedance phase measurementaccuracy. The determination of phase impedance and a frequency controlsignal may be implemented in the processor 174, for example, with thefrequency control signal being supplied as input to a DDS controlalgorithm implemented by the programmable logic device 166.

In another aspect, for example, the current feedback data may bemonitored in order to maintain the current amplitude of the drive signalat a current amplitude setpoint. The current amplitude setpoint may bespecified directly or determined indirectly based on specified voltageamplitude and power setpoints. In certain aspects, control of thecurrent amplitude may be implemented by control algorithm, such as, forexample, a proportional-integral-derivative (PID) or aproportional-integral (PI) control algorithm, in the processor 174.Variables controlled by the control algorithm to suitably control thecurrent amplitude of the drive signal may include, for example, thescaling of the LUT waveform samples stored in the programmable logicdevice 166 and/or the full-scale output voltage of the DAC 168 (whichsupplies the input to the power amplifier 162) via a DAC 186.

The non-isolated stage 154 may further comprise a processor 190 forproviding, among other things user interface (UI) functionality. In oneaspect, the processor 190 may comprise an Atmel AT91 SAM9263 processorhaving an ARM 926EJ-S core, available from Atmel Corporation, San Jose,Calif., for example. Examples of UI functionality supported by theprocessor 190 may include audible and visual user feedback,communication with peripheral devices (e.g., via a Universal Serial Bus(USB) interface), communication with the footswitch 120, communicationwith an input device 145 (e.g., a touch screen display) andcommunication with an output device 146 (e.g., a speaker). The processor190 may communicate with the processor 174 and the programmable logicdevice (e.g., via serial peripheral interface (SPI) buses). Although theprocessor 190 may primarily support UI functionality, it may alsocoordinate with the processor 174 to implement hazard mitigation incertain aspects. For example, the processor 190 may be programmed tomonitor various aspects of user input and/or other inputs (e.g., touchscreen inputs, footswitch 120 inputs, temperature sensor inputs) and maydisable the drive output of the generator 102 when an erroneouscondition is detected.

In certain aspects, both the processor 174 and the processor 190 maydetermine and monitor the operating state of the generator 102. For theprocessor 174, the operating state of the generator 102 may dictate, forexample, which control and/or diagnostic processes are implemented bythe processor 174. For the processor 190, the operating state of thegenerator 102 may dictate, for example, which elements of a userinterface (e.g., display screens, sounds) are presented to a user. Theprocessors 174, 190 may independently maintain the current operatingstate of the generator 102 and recognize and evaluate possibletransitions out of the current operating state. The processor 174 mayfunction as the master in this relationship and determine whentransitions between operating states are to occur. The processor 190 maybe aware of valid transitions between operating states and may confirmif a particular transition is appropriate. For example, when theprocessor 174 instructs the processor 190 to transition to a specificstate, the processor 190 may verify that requested transition is valid.In the event that a requested transition between states is determined tobe invalid by the processor 190, the processor 190 may cause thegenerator 102 to enter a failure mode.

The non-isolated stage 154 may further comprise a controller 196 formonitoring input devices 145 (e.g., a capacitive touch sensor used forturning the generator 102 on and off, a capacitive touch screen). Incertain aspects, the controller 196 may comprise at least one processorand/or other controller device in communication with the processor 190.In one aspect, for example, the controller 196 may comprise a processor(e.g., a Mega168 8-bit controller available from Atmel) configured tomonitor user input provided via one or more capacitive touch sensors. Inone aspect, the controller 196 may comprise a touch screen controller(e.g., a QT5480 touch screen controller available from Atmel) to controland manage the acquisition of touch data from a capacitive touch screen.

In certain aspects, when the generator 102 is in a “power off’ state,the controller 196 may continue to receive operating power (e.g., via aline from a power supply of the generator 102, such as the power supply211 discussed below). In this way, the controller 196 may continue tomonitor an input device 145 (e.g., a capacitive touch sensor located ona front panel of the generator 102) for turning the generator 102 on andoff. When the generator 102 is in the power off state, the controller196 may wake the power supply (e.g., enable operation of one or moreDC/DC voltage converters 213 of the power supply 211) if activation ofthe “on/off’ input device 145 by a user is detected. The controller 196may therefore initiate a sequence for transitioning the generator 102 toa “power on” state. Conversely, the controller 196 may initiate asequence for transitioning the generator 102 to the power off state ifactivation of the “on/off’ input device 145 is detected when thegenerator 102 is in the power on state. In certain aspects, for example,the controller 196 may report activation of the “on/off’ input device145 to the processor 190, which in tum implements the necessary processsequence for transitioning the generator 102 to the power off state. Insuch aspects, the controller 196 may have no independent ability forcausing the removal of power from the generator 102 after its power onstate has been established.

In certain aspects, the controller 196 may cause the generator 102 toprovide audible or other sensory feedback for alerting the user that apower on or power off sequence has been initiated. Such an alert may beprovided at the beginning of a power on or power off sequence and priorto the commencement of other processes associated with the sequence.

In certain aspects, the isolated stage 152 may comprise an instrumentinterface circuit 198 to, for example, provide a communication interfacebetween a control circuit of a surgical device (e.g., a control circuitcomprising handpiece switches) and components of the non-isolated stage154, such as, for example, the programmable logic device 166, theprocessor 174 and/or the processor 190. The instrument interface circuit198 may exchange information with components of the non-isolated stage154 via a communication link that maintains a suitable degree ofelectrical isolation between the stages 152, 154, such as, for example,an infrared (IR)-based communication link. Power may be supplied to theinstrument interface circuit 198 using, for example, a low-dropoutvoltage regulator powered by an isolation transformer driven from thenon-isolated stage 154.

In one aspect, the instrument interface circuit 198 may comprise aprogrammable logic device 200 (e.g., an FPGA) in communication with asignal conditioning circuit 202. The signal conditioning circuit 202 maybe configured to receive a periodic signal from the programmable logicdevice 200 (e.g., a 2 kHz square wave) to generate a bipolarinterrogation signal having an identical frequency. The interrogationsignal may be generated, for example, using a bipolar current source fedby a differential amplifier. The interrogation signal may becommunicated to a surgical device control circuit (e.g., by using aconductive pair in a cable that connects the generator 102 to thesurgical device) and monitored to determine a state or configuration ofthe control circuit. The control circuit may comprise a number ofswitches, resistors and/or diodes to modify one or more characteristics(e.g., amplitude, rectification) of the interrogation signal such that astate or configuration of the control circuit is uniquely discernablebased on the one or more characteristics. In one aspect, for example,the signal conditioning circuit 202 may comprise an ADC for generatingsamples of a voltage signal appearing across inputs of the controlcircuit resulting from passage of interrogation signal therethrough. Theprogrammable logic device 200 (or a component of the nonisolated stage154) may then determine the state or configuration of the controlcircuit based on the ADC samples.

In one aspect, the instrument interface circuit 198 may comprise a firstdata circuit interface 204 to enable information exchange between theprogrammable logic device 200 (or other element of the instrumentinterface circuit 198) and a first data circuit disposed in or otherwiseassociated with a surgical device. In certain aspects, a first datacircuit 206 may be disposed in a cable integrally attached to a surgicaldevice handpiece, or in an adaptor for interfacing a specific surgicaldevice type or model with the generator 102. In certain aspects, thefirst data circuit may comprise a non-volatile storage device, such asan electrically erasable programmable read-only memory (EEPROM) device.In certain aspects and referring again to FIG. 7, the first data circuitinterface 204 may be implemented separately from the programmable logicdevice 200 and comprise suitable circuitry (e.g., discrete logicdevices, a processor) to enable communication between the programmablelogic device 200 and the first data circuit. In other aspects, the firstdata circuit interface 204 may be integral with the programmable logicdevice 200.

In certain aspects, the first data circuit 206 may store informationpertaining to the particular surgical device with which it isassociated. Such information may include, for example, a model number, aserial number, a number of operations in which the surgical device hasbeen used, and/or any other type of information. This information may beread by the instrument interface circuit 198 (e.g., by the programmablelogic device 200), transferred to a component of the non-isolated stage154 (e.g., to programmable logic device 166, processor 174 and/orprocessor 190) for presentation to a user via an output device 146and/or for controlling a function or operation of the generator 102.Additionally, any type of information may be communicated to first datacircuit 206 for storage therein via the first data circuit interface 204(e.g., using the programmable logic device 200). Such information maycomprise, for example, an updated number of operations in which thesurgical device has been used and/or dates and/or times of its usage.

A surgical instrument may be detachable from a handpiece to promoteinstrument interchangeability and/or disposability. In such cases, knowngenerators may be limited in their ability to recognize particularinstrument configurations being used and to optimize control anddiagnostic processes accordingly. The addition of readable data circuitsto surgical device instruments to address this issue is problematic froma compatibility standpoint, however. For example, designing a surgicaldevice to remain backwardly compatible with generators that lack therequisite data reading functionality may be impractical due to, forexample, differing signal schemes, design complexity and cost. Aspectsof instruments may use data circuits that may be implemented in existingsurgical instruments economically and with minimal design changes topreserve compatibility of the surgical devices with current generatorplatforms.

Additionally, aspects of the generator 102 may enable communication withinstrument-based data circuits. For example, the generator 102 may beconfigured to communicate with a second data circuit contained in aninstrument of a surgical device. The instrument interface circuit 198may comprise a second data circuit interface 210 to enable thiscommunication. In one aspect, the second data circuit interface 210 maycomprise a tri-state digital interface, although other interfaces mayalso be used. In certain aspects, the second data circuit may generallybe any circuit for transmitting and/or receiving data. In one aspect,for example, the second data circuit may store information pertaining tothe particular surgical instrument with which it is associated. Suchinformation may include, for example, a model number, a serial number, anumber of operations in which the surgical instrument has been used,and/or any other type of information. Additionally or alternatively, anytype of information may be communicated to second data circuit forstorage therein via the second data circuit interface 210 (e.g., usingthe programmable logic device 200). Such information may comprise, forexample, an updated number of operations in which the instrument hasbeen used and/or dates and/or times of its usage. In certain aspects,the second data circuit may transmit data acquired by one or moresensors (e.g., an instrument-based temperature sensor). In certainaspects, the second data circuit may receive data from the generator 102and provide an indication to a user (e.g., an LED indication or othervisible indication) based on the received data.

In certain aspects, the second data circuit and the second data circuitinterface 210 may be configured such that communication between theprogrammable logic device 200 and the second data circuit can beeffected without the need to provide additional conductors for thispurpose (e.g., dedicated conductors of a cable connecting a handpiece tothe generator 102). In one aspect, for example, information may becommunicated to and from the second data circuit using a 1-wire buscommunication scheme implemented on existing cabling, such as one of theconductors used transmit interrogation signals from the signalconditioning circuit 202 to a control circuit in a handpiece. In thisway, design changes or modifications to the surgical device that mightotherwise be necessary are minimized or reduced. Moreover, becausedifferent types of communications can be implemented over a commonphysical channel (either with or without frequency-band separation), thepresence of a second data circuit may be “invisible” to generators thatdo not have the requisite data reading functionality, thus enablingbackward compatibility of the surgical device instrument. In certainaspects, the isolated stage 152 may comprise at least one blockingcapacitor 296-1 connected to the drive signal output 160 b to preventpassage of DC current to a patient. A single blocking capacitor may berequired to comply with medical regulations or standards, for example.While failure in single-capacitor designs is relatively uncommon, suchfailure may nonetheless have negative consequences. In one aspect, asecond blocking capacitor 296-2 may be provided in series with theblocking capacitor 296-1, with current leakage from a point between theblocking capacitors 296-1, 296-2 being monitored by, for example, an ADC298 for sampling a voltage induced by leakage current. The samples maybe received by the programmable logic device 200, for example. Based onchanges in the leakage current (as indicated by the voltage samples inthe aspect of FIG. 7), the generator 102 may determine when at least oneof the blocking capacitors 296-1, 296-2 has failed. Accordingly, theaspect of FIG. 7 may provide a benefit over single-capacitor designshaving a single point of failure.

In certain aspects, the non-isolated stage 154 may comprise a powersupply 211 for outputting DC power at a suitable voltage and current.The power supply may comprise, for example, a 400 W power supply foroutputting a 48 VDC system voltage. The power supply 211 may furthercomprise one or more DC/DC voltage converters 213 for receiving theoutput of the power supply to generate DC outputs at the voltages andcurrents required by the various components of the generator 102. Asdiscussed above in connection with the controller 196, one or more ofthe DC/DC voltage converters 213 may receive an input from thecontroller 196 when activation of the “on/off’ input device 145 by auser is detected by the controller 196 to enable operation of, or wake,the DC/DC voltage converters 213.

FIGS. 10A and 10B illustrate certain functional and structural aspectsof one aspect of the generator 102. Feedback indicating current andvoltage output from the secondary winding 158 of the power transformer156 is received by the ADCs 178, 180, respectively. As shown, the ADCs178, 180 may be implemented as a 2-channel ADC and may sample thefeedback signals at a high speed (e.g., 80 Msps) to enable oversampling(e.g., approximately 200×oversampling) of the drive signals. The currentand voltage feedback signals may be suitably conditioned in the analogdomain (e.g., amplified, filtered) prior to processing by the ADCs 178,180. Current and voltage feedback samples from the ADCs 178, 180 may beindividually buffered and subsequently multiplexed or interleaved into asingle data stream within block 212 of the programmable logic device166. In the aspect of FIGS. 10A and 10B, the programmable logic device166 comprises an FPGA.

The multiplexed current and voltage feedback samples may be received bya parallel data acquisition port (PDAP) implemented within block 214 ofthe processor 174. The PDAP may comprise a packing unit for implementingany of a number of methodologies for correlating the multiplexedfeedback samples with a memory address. In one aspect, for example,feedback samples corresponding to a particular LUT sample output by theprogrammable logic device 166 may be stored at one or more memoryaddresses that are correlated or indexed with the LUT address of the LUTsample. In another aspect, feedback samples corresponding to aparticular LUT sample output by the programmable logic device 166 may bestored, along with the LUT address of the LUT sample, at a common memorylocation. In any event, the feedback samples may be stored such that theaddress of an LUT sample from which a particular set of feedback samplesoriginated may be subsequently ascertained. As discussed above,synchronization of the LUT sample addresses and the feedback samples inthis way contributes to the correct timing and stability of thepre-distortion algorithm. A direct memory access (DMA) controllerimplemented at block 216 of the processor 174 may store the feedbacksamples (and any LUT sample address data, where applicable) at adesignated memory location 218 of the processor 174 (e.g., internalRAM).

Block 220 of the processor 174 may implement a pre-distortion algorithmfor pre-distorting or modifying the LUT samples stored in theprogrammable logic device 166 on a dynamic, ongoing basis. As discussedabove, pre-distortion of the LUT samples may compensate for varioussources of distortion present in the output drive circuit of thegenerator 102. The pre-distorted LUT samples, when processed through thedrive circuit, will therefore result in a drive signal having thedesired waveform shape (e.g., sinusoidal) for optimally driving theultrasonic transducer.

At block 222 of the pre-distortion algorithm, the current through themotional branch of the ultrasonic transducer is determined. The motionalbranch current may be determined using Kirchoffs Current Law based on,for example, the current and voltage feedback samples stored at memorylocation 218, a value of the ultrasonic transducer static capacitance Co(measured or known a priori) and a known value of the drive frequency. Amotional branch current sample for each set of stored current andvoltage feedback samples associated with a LUT sample may be determined.

At block 224 of the pre-distortion algorithm, each motional branchcurrent sample determined at block 222 is compared to a sample of adesired current waveform shape to determine a difference, or sampleamplitude error, between the compared samples. For this determination,the sample of the desired current waveform shape may be supplied, forexample, from a waveform shape LUT 226 containing amplitude samples forone cycle of a desired current waveform shape. The particular sample ofthe desired current waveform shape from the LUT 226 used for thecomparison may be dictated by the LUT sample address associated with themotional branch current sample used in the comparison. Accordingly, theinput of the motional branch current to block 224 may be synchronizedwith the input of its associated LUT sample address to block 224. TheLUT samples stored in the programmable logic device 166 and the LUTsamples stored in the waveform shape LUT 226 may therefore be equal innumber. In certain aspects, the desired current waveform shaperepresented by the LUT samples stored in the waveform shape LUT 226 maybe a fundamental sine wave. Other waveform shapes may be desirable. Forexample, it is contemplated that a fundamental sine wave for drivingmain longitudinal motion of an ultrasonic transducer superimposed withone or more other drive signals at other frequencies, such as a thirdorder ultrasonic for driving at least two mechanical resonances forbeneficial vibrations of transverse or other modes, could be used.

Each value of the sample amplitude error determined at block 224 may betransmitted to the LUT of the programmable logic device 166 (shown atblock 228 in FIG. 10A) along with an indication of its associated LUTaddress. Based on the value of the sample amplitude error and itsassociated address (and, optionally, values of sample amplitude errorfor the same LUT address previously received), the LUT 228 (or othercontrol block of the programmable logic device 166) may pre-distort ormodify the value of the LUT sample stored at the LUT address such thatthe sample amplitude error is reduced or minimized. It will beappreciated that such pre-distortion or modification of each LUT samplein an iterative manner across the entire range of LUT addresses willcause the waveform shape of the generator's output current to match orconform to the desired current waveform shape represented by the samplesof the waveform shape LUT 226.

Current and voltage amplitude measurements, power measurements andimpedance measurements may be determined at block 230 of the processor174 based on the current and voltage feedback samples stored at memorylocation 218. Prior to the determination of these quantities, thefeedback samples may be suitably scaled and, in certain aspects,processed through a suitable filter 232 to remove noise resulting from,for example, the data acquisition process and induced ultrasoniccomponents. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal. In certain aspects, the filter 232 may be a finiteimpulse response (FIR) filter applied in the frequency domain. Suchaspects may use the fast Fourier transform (FFT) of the output drivesignal current and voltage signals. In certain aspects, the resultingfrequency spectrum may be used to provide additional generatorfunctionality. In one aspect, for example, the ratio of the secondand/or third order ultrasonic component relative to the fundamentalfrequency component may be used as a diagnostic indicator. At block 234,a root mean square (RMS) calculation may be applied to a sample size ofthe current feedback samples representing an integral number of cyclesof the drive signal to generate a measurement Irms representing thedrive signal output current.

At block 236, a root mean square (RMS) calculation may be applied to asample size of the voltage feedback samples representing an integralnumber of cycles of the drive signal to determine a measurement Vrmsrepresenting the drive signal output voltage. At block 238, the currentand voltage feedback samples may be multiplied point by point, and amean calculation is applied to samples representing an integral numberof cycles of the drive signal to determine a measurement Pr of thegenerator's real output power.

At block 240, measurement Pa of the generator's apparent output powermay be determined as the product Vrms·Irms.

At block 242, measurement Zm of the load impedance magnitude may bedetermined as the quotient Vrms/Irms.

In certain aspects, the quantities Irms, Vrms, Pr, Pa, and Zm determinedat blocks 234, 236, 238, 240 and 242 may be used by the generator 102 toimplement any of number of control and/or diagnostic processes. Incertain aspects, any of these quantities may be communicated to a uservia, for example, an output device 146 integral with the generator 102or an output device 146 connected to the generator 102 through asuitable communication interface (e.g., a USB interface). Variousdiagnostic processes may include, without limitation, handpieceintegrity, instrument integrity, instrument attachment integrity,instrument overload, approaching instrument overload, frequency lockfailure, over-voltage, over-current, over-power, voltage sense failure,current sense failure, audio indication failure, visual indicationfailure, short circuit, power delivery failure, blocking capacitorfailure, for example.

Block 244 of the processor 174 may implement a phase control algorithmfor determining and controlling the impedance phase of an electricalload (e.g., the ultrasonic transducer) driven by the generator 102. Asdiscussed above, by controlling the frequency of the drive signal tominimize or reduce the difference between the determined impedance phaseand an impedance phase setpoint (e.g., 0°), the effects of ultrasonicdistortion may be minimized or reduced, and the accuracy of the phasemeasurement increased.

The phase control algorithm receives as input the current and voltagefeedback samples stored in the memory location 218. Prior to their usein the phase control algorithm, the feedback samples may be suitablyscaled and, in certain aspects, processed through a suitable filter 246(which may be identical to filter 232) to remove noise resulting fromthe data acquisition process and induced ultrasonic components, forexample. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal.

At block 248 of the phase control algorithm, the current through themotional branch of the ultrasonic transducer is determined. Thisdetermination may be identical to that described above in connectionwith block 222 of the pre-distortion algorithm. The output of block 248may thus be, for each set of stored current and voltage feedback samplesassociated with a LUT sample, a motional branch current sample.

At block 250 of the phase control algorithm, impedance phase isdetermined based on the synchronized input of motional branch currentsamples determined at block 248 and corresponding voltage feedbacksamples. In certain aspects, the impedance phase is determined as theaverage of the impedance phase measured at the rising edge of thewaveforms and the impedance phase measured at the falling edge of thewaveforms.

At block 252 of the of the phase control algorithm, the value of theimpedance phase determined at block 222 is compared to phase setpoint254 to determine a difference, or phase error, between the comparedvalues.

At block 256 of the phase control algorithm, based on a value of phaseerror determined at block 252 and the impedance magnitude determined atblock 242, a frequency output for controlling the frequency of the drivesignal is determined. The value of the frequency output may becontinuously adjusted by the block 256 and transferred to a DDS controlblock 268 (discussed below) in order to maintain the impedance phasedetermined at block 250 at the phase setpoint (e.g., zero phase error).In certain aspects, the impedance phase may be regulated to a oo phasesetpoint. In this way, any ultrasonic distortion will be centered aboutthe crest of the voltage waveform, enhancing the accuracy of phaseimpedance determination.

Block 258 of the processor 174 may implement an algorithm for modulatingthe current amplitude of the drive signal in order to control the drivesignal current, voltage and power in accordance with user specifiedsetpoints, or in accordance with requirements specified by otherprocesses or algorithms implemented by the generator 102. Control ofthese quantities may be realized, for example, by scaling the LUTsamples in the LUT 228 and/or by adjusting the full-scale output voltageof the DAC 168 (which supplies the input to the power amplifier 162) viaa DAC 186. Block 260 (which may be implemented as a PID controller incertain aspects) may receive as input current feedback samples (whichmay be suitably scaled and filtered) from the memory location 218. Thecurrent feedback samples may be compared to a “current demand” Id valuedictated by the controlled variable (e.g., current, voltage or power) todetermine if the drive signal is supplying the necessary current. Inaspects in which drive signal current is the control variable, thecurrent demand Id may be specified directly by a current setpoint 262A(Isp). For example, an RMS value of the current feedback data(determined as in block 234) may be compared to user-specified RMScurrent setpoint Isp to determine the appropriate controller action. If,for example, the current feedback data indicates an RMS value less thanthe current setpoint Isp, LUT scaling and/or the full-scale outputvoltage of the DAC 168 may be adjusted by the block 260 such that thedrive signal current is increased. Conversely, block 260 may adjust LUTscaling and/or the full-scale output voltage of the DAC 168 to decreasethe drive signal current when the current feedback data indicates an RMSvalue greater than the current setpoint Isp.

In aspects in which the drive signal voltage is the control variable,the current demand Id may be specified indirectly, for example, based onthe current required to maintain a desired voltage setpoint 262B (Vsp)given the load impedance magnitude Zm measured at block 242 (e.g.Id=Vsp/Zm). Similarly, in aspects in which drive signal power is thecontrol variable, the current demand Id may be specified indirectly, forexample, based on the current required to maintain a desired powersetpoint 262C (Psp) given the voltage Vrms measured at blocks 236 (e.g.Id=Psp/Vrms).

Block 268 may implement a DDS control algorithm for controlling thedrive signal by recalling LUT samples stored in the LUT 228. In certainaspects, the DDS control algorithm be a numerically-controlledoscillator (NCO) algorithm for generating samples of a waveform at afixed clock rate using a point (memory location)-skipping technique. TheNCO algorithm may implement a phase accumulator, or frequency-to-phaseconverter, that functions as an address pointer for recalling LUTsamples from the LUT 228. In one aspect, the phase accumulator may be aD step size, modulo N phase accumulator, where D is a positive integerrepresenting a frequency control value, and N is the number of LUTsamples in the LUT 228. A frequency control value of D=1, for example,may cause the phase accumulator to sequentially point to every addressof the LUT 228, resulting in a waveform output replicating the waveformstored in the LUT 228. When D>1, the phase accumulator may skipaddresses in the LUT 228, resulting in a waveform output having a higherfrequency. Accordingly, the frequency of the waveform generated by theDDS control algorithm may therefore be controlled by suitably varyingthe frequency control value. In certain aspects, the frequency controlvalue may be determined based on the output of the phase controlalgorithm implemented at block 244. The output of block 268 may supplythe input of (DAC) 168, which in tum supplies a corresponding analogsignal to an input of the power amplifier 162.

Block 270 of the processor 174 may implement a switch-mode convertercontrol algorithm for dynamically modulating the rail voltage of thepower amplifier 162 based on the waveform envelope of the signal beingamplified, thereby improving the efficiency of the power amplifier 162.In certain aspects, characteristics of the waveform envelope may bedetermined by monitoring one or more signals contained in the poweramplifier 162. In one aspect, for example, characteristics of thewaveform envelope may be determined by monitoring the minima of a drainvoltage (e.g., a MOSFET drain voltage) that is modulated in accordancewith the envelope of the amplified signal. A minima voltage signal maybe generated, for example, by a voltage minima detector coupled to thedrain voltage. The minima voltage signal may be sampled by ADC 176, withthe output minima voltage samples being received at block 272 of theswitch-mode converter control algorithm. Based on the values of theminima voltage samples, block 274 may control a PWM signal output by aPWM generator 276, which, in turn, controls the rail voltage supplied tothe power amplifier 162 by the switch-mode regulator 170. In certainaspects, as long as the values of the minima voltage samples are lessthan a minima target 278 input into block 262, the rail voltage may bemodulated in accordance with the waveform envelope as characterized bythe minima voltage samples. When the minima voltage samples indicate lowenvelope power levels, for example, block 274 may cause a low railvoltage to be supplied to the power amplifier 162, with the full railvoltage being supplied only when the minima voltage samples indicatemaximum envelope power levels. When the minima voltage samples fallbelow the minima target 278, block 274 may cause the rail voltage to bemaintained at a minimum value suitable for ensuring proper operation ofthe power amplifier 162.

In one aspect, a method and/or apparatus may provide functionality forsensing a clamp arm position relative to a ultrasonic blade of an endeffector, and a generator such as generator 102 and a controller such ascontrol circuit 108 and/or controller 196 may be used to adjust a poweroutput to the ultrasonic blade based on the clamp arm position.Referring now to FIG. 32, a process 3200 for controlling an end effectoris shown. The process 3200 may be executed at least in part by aprocessor which may be in communication with or may be part of one ormore of generator 102, control circuit 108, and/or controller 196.Referring now to FIG. 32, a process 3300 for calibrating a controllerfor an end effector is shown. The process 3200 may be executed at leastin part by a processor which may be in communication with or may be partof one or more of generator 102, control circuit 108, and/or controller196.

Referring now to FIG. 11, an example end effector 300 and shaft 302 areshown. The clamp arm 304 may have a position (e.g., represented by the“angle” arrow or a displacement) relative to the ultrasonic blade 306,which may be measured using one or more sensors such as Hall-effectsensor. Sensing the position of the clamp arm relative to the ultrasonicblade may provide relevant device information enabling new capabilitiessuch as the ability to sense thickness, quantity, or types of tissuesclamped inside the jaws. In one aspect, the process 3200 of FIG. 32 maydetermine 3220 a type of tissue between the clamp arm and the ultrasonicblade based on a signal (from, e.g., a Hall-effect sensor). Further,using a processor and/or memory, one or more algorithms (e.g., forsealing a vessel without transection) may be chosen based on thethickness, quantity, or type of tissue determined to be clamped insidethe jaws.

Ultrasonic blade 306 may deliver a tissue effect through mechanicalvibration to tissues and/or blood vessels. Clamp arm 304 may pivot aboutpoint 314, which may represent a connection between the clamp arm and anouter tube 310. An inner tube 308 may move back and forth and may driveclosure of the clamp arm 304 on ultrasonic blade 306. In variousaspects, it may be desirable to measure the angle between the clamp arm304 and the ultrasonic blade 306.

In one aspect, the position of clamp arm 304 relative to ultrasonicblade 306 (e.g., during activation) may be approximated through acoupling with the inner tube 308. The inner tube 308 may be linked tothe clamp arm 304 and may be similar to the reciprocating tubularactuating member 58 located within the outer tubular sheath 56. Theouter tube 310, which may be similar to the outer tubular sheath 56,and/or ultrasonic blade 306, may be used to determine a position and/orangle of the clamp arm 304 relative to ultrasonic blade 306. The outertube 310 may be static and in one aspect may be linked to clamp arm 304.As result, using the techniques and features described herein, themovement (e.g., represented with the bidirectional arrow 312) of theinner tube 308 relative to the outer tube 310 may be measured and usedto approximate the claim arm position.

Referring briefly to FIG. 32, process 3200 may detect 3202 a signal(e.g., at a Hall-effect sensor) in response to movement of a first tuberelative to a second tube, the first tube driving movement of a clamparm of the end effector. The first tube may be, for example, similar toreciprocating tubular actuating member 58 and the second tube may be,for example, similar to outer tubular sheath 56. In other words, asdescribed in FIG. 32, the first tube may be an inner tube and the secondtube is an outer tube. The inner tube may be moveable 3208 relative tothe outer tube. The outer tube may be static relative to the inner tube.The process 3200 may detect 3210 the signal using a Hall-effect sensorand a magnet positioned on the first tube.

Use of Hall-effect sensors will be described herein with respect tovarious aspects of the present disclosure, however other types ofsensors may be used to measure the movement 312. For example, linearvariable differential transformers (LVDT), rotary variable differentialtransformer, piezoelectric transducers, potentiometers, photo electricsensors may be used to measure the movement 312. Furthermore,Hall-effect sensors and suitable equivalents may be used to measure theposition of two bodies relative to one another through the use of asmall electronic board and magnets.

Referring now to FIG. 12, a representation of an example Hall-effectsensor is shown. A magnet 402 may have north and south poles which movein a line perpendicular to the face of the Hall sensor 404, which may bein a fixed position. Referring now to FIG. 13A, another representationof an example Hall-effect sensor is shown. A magnet 408 may have northand south poles moving in a line parallel to the face of the Hall-effectsensor 410, which may be in a fixed position. Referring now to FIG. 13B,another representation of an example Hall-effect sensor is shown. Amagnet 414 may have north and south poles moving in a line (418)parallel to the face of the Hall-effect sensor 416, which may be in afixed position. The magnet may have diameter D and the magnet andHall-effect sensor 416 may have total effective air gap (TEAG) 420. Thisconfiguration may allow for a very sensitive measurement of movementover small distances with the appropriate magnet-sensor combination.

The Hall-effect sensor may include a small electronic chip which maysense magnetic fields and change its electrical output based on therelative proximity of the magnet or the strength of the magnetic fieldsto the Hall-effect sensor. As the magnet moves across the face of theHall-effect sensor (e.g., marked “X”) and gets closer to being directlyin front of the face, an output signal of the Hall-effect sensor maychange and be used to determine a position of the magnet relative to theHall-effect sensor. In one aspect, the magnet may not cause much of achange in the output signal of the Hall-effect sensor. For example,using a magnet and Hall-effect sensor having particular characteristics,the magnet being more than 1.5 inches or further distances from theHall-effect sensor may produce very little in terms of the outputsignal, but as the magnet moves closer and closer to the Hall-effectsensor, the electrical output changes more rapidly such that a verydiscernable signal change occurs in response to small motions of themagnet as it is moved closer to a critical position. The electricalresponse of the Hall-effect sensor at various positions of the magnetmay be used to create a best fit curve. For example, the voltage outputof the Hall-effect sensor as a function of the displacement of themagnet may be determined.

FIG. 14A is a table 1400 of output voltage of a Hall-effect sensor as afunction of distance as a clamp arm moves from a fully closed positionto a fully open position in accordance with the present disclosure.Relative distance (mm) is listed in the first column 1402. Absolutedistance (mm) is listed in the second column 1404 and absolute distancein inches is listed in the third column 1406. Output voltage of theHall-effect sensor is listed in the fourth column 1408 and clamp armposition is listed in the fifth column 1410, where the uppermost cellindicates the clamp arm in the fully closed position and the lowermostcell indicates the clamp arm in the fully open position.

Referring now to FIGS. 14A and 14B, a table 1400 and a graph 1450 of theoutput voltage of a Hall-effect sensor (y-axis) as a function of thedisplacement (x-axis) and related data are shown. In this example, thesensitivity of a prototyped Hall-effect sensor/magnet combination isshown as a relatively small linear movement (e.g., 0.100″) may result ina 1.5 volts signal change. This signal change may be read by a generator(e.g., generator 102) and used to make determinations about ultrasonicblade displacement, or provide auditory, tactile and/or other feedbackto a user (e.g., via speaker 114 and/or visual display 116). A best fitcurve 1452 may be determined from the plotted data points 145 a-h (e.g.,one or more of relative displacement, absolute displacement, voltageoutput, and position) and a polynomial equation for output voltage ofthe Hall-effect sensor (y-axis) as a function of the displacement(x-axis) of the magnet may result. The best fit curve may be of the 2nd,3rd, 4th . . . nth order. The data points 1454 a-h and/or the best fitcurve 1452 may be used to create a lookup table stored in a memoryand/or the resulting equation may be executed in a processor in order todetermine, for example, a displacement for the magnet (and acorresponding clamp arm position) given a specific output voltage of theHall-effect sensor. In this way, turning briefly to FIG. 32, the process3200 may determine 3204 a clamp arm position of the end effectorrelative to a ultrasonic blade of the end effector based on the signal(from, e.g., Hall-effect sensor voltage output).

Turning now to FIG. 15A there is shown a top view of a Hall-effectsensor 510 and magnet 508 configurations in a surgical instrument andcorresponding open jaws end effector 500 position in accordance with oneaspect of the present disclosure and FIG. 15B is a top view of theHall-effect sensor 510 and magnet 508 configurations in a surgicalinstrument and corresponding closed jaws end effector 500 position inaccordance with one aspect of the present disclosure. In one aspect, asshown in FIGS. 15A and 15B, the voltage output of the Hall-effect sensor50 is 1.6 VDC when the jaws of the end effector 500 are open and 3.1 VDCwhen the jaws of the end effector 500 are closed.

Referring now to FIGS. 15A and 15B, one aspect of a Hall-effect sensor510 and magnet 508 combination are shown as implemented in a surgicaldevice such as one or more of those discussed herein. FIGS. 15A and 15Bshow two images of top-down views of the example. An inner threadedcollar 502 may be attached to a magnet 508. As a trigger of the surgicaldevice is closed, a clamp arm 504 of the end effector 500 comes intocloser contact with a ultrasonic blade 504, and the magnet 508 movesfurther proximal as shown in the top-down views. As the magnet 508 moves(in a direction indicated by arrow 506), the voltage potential of theHall-effect sensor 510 changes. The magnet 508 positioned on the firsttube relative to the Hall-effect sensor 510 may move as the first tubedrives movement of the clamp arm 503 of the end effector 500.

It should be noted that while various aspects discussed herein aredescribed to include an outer tube that is static and an inner tube thatdrives motion of the clamp arm, other configurations are possible andwithin the scope of the present disclosure. For example, in variousaspects, an outer tube may drive the motion of the clamp arm and theinner tube may be static. Additionally, while various aspects discussedherein are described to include a Hall-effect sensor 510 and/orintegrated circuit (e.g., chip) that is static and a magnet 508 thatmoves as the clamp arm 500 moves, other configurations are possible andwithin the scope of the present disclosure. For example, in variousaspects, the Hall-effect sensor 510 may move as the clamp arm 503 movesand the magnet may be static. Many combinations are possible, includinga fixed outer tube and a moveable inner, a moving magnet 508 and astationery Hall-effect sensor 510 or other sensing circuit, a movingHall-effect sensor 510 or other sensing circuit and a stationary magnet508, a moveable outer tube and a fixed inner tube, a fixed magnet in oneof the inner and outer tubes, and/or a moving magnet in one of the innerand outer tubes. The Hall-effect sensor 510 or other circuit may bemounted to the moving part (e.g., inner or outer tube) or mounted to thestationary part (e.g., inner or outer tube), as long as flexibleelectrical connections are considered and motion can be achieved.

As shown in FIG. 15A, the inner threaded collar 502 with attached magnet508 is positioned further left than in FIG. 15B, and the correspondingend effector 500 has an open jaw, e.g., open clamp arm 503. As the userpulls the trigger and closes the end effector 500, multiple springs andthe inner threaded collar 502 move (in the direction indicated by arrow506) the clamp arm 503 is driven closed or is driven to grafting tissuecaptured in between the clamp arm 503 and the ultrasonic blade 504. AHall-effect sensor 510 and a magnet 508 is shown, which may becylindrical, moves over the Hall-effect sensor 510, as the clamp arm 503closes towards the ultrasonic blade 504.

Referring now to FIG. 16, there is shown a plan view of a system 600comprising a Hall-effect sensor 602 and magnet 606 arrangement. TheHall-effect sensor 602 includes a circuit board 604 and an integratedcircuit 606. The magnet 608 moves back and forth along line 610 as theclamp arm is closed and opened. As the magnet 608 moves towards thecenter of the Hall effect integrated circuit 606 the sensitivity of theHall-effect sensor 602 changes and the output signal increases. Acarrier 612 for the magnet 608 may be coupled to the inner tube thatdrives the clamp arm. In one aspect, as the inner tube is pulled towardsthe handle of the surgical instrument (e.g., by the trigger), the jawcloses (e.g., clamp arm) closes. The magnet 608 is connected to anextended leg of the threaded inner collar of the outer tube.

FIGS. 17A and 17B illustrates different views of the system 600comprising a Hall-effect sensor 602 and magnet 608 configurations in thecontext of a surgical instrument in accordance with one aspect of thepresent disclosure. With reference to FIGS. 17A and 17B, the Hall-effectsensor 602 is shown positioned within a surgical instrument. TheHall-effect sensor 602 is positioned on the threaded inner collar 620 ofthe outer tube 622. A slot 624 is defined in a rotation knob of theouter tube 622 to allow the magnet 608 to travel. The magnet 608 ispositioned within the carrier 612, which is slidably movable within theslot 624. For example, the Hall-effect sensor 602 as described hereinmay be static and is attached to a rotation knob such that it can rotatearound the centerline of the ultrasonic blade. A pin 626 may bepositioned within an aperture 628 through both the rotation knob and theHall-effect sensor 602 and through a center ultrasonic blade portion. Asa result, the ultrasonic blade does not move axially, but the inner tubeis able to move axially right and left of the pin 626. A threadedconnection 630 is made of nylon or any other suitable material withminimum magnetic flux.

FIG. 18 illustrates a Hall-effect sensor 602 and magnet 608configuration in the context of a surgical instrument in accordance withthe present disclosure. Referring now to FIG. 18, a shaft of a surgicalinstrument is shown and the magnet 608 is positioned within the carrier612. A magnet movement 632 is coupled to the inner tube 634. The magnet608 may be coupled with snap fits to a threaded collar 638 of the innertube 634. The Hall-effect sensor 602 as described herein is static andis attached to a rotation knob such that it can rotate around thecenterline of the ultrasonic blade.

FIG. 19A illustrates a Hall-effect sensor 602 and magnet 608configuration in accordance with one aspect of the present disclosure.FIG. 19B is a detailed view of the Hall-effect sensor 602 and magnet 608configuration in the context of a surgical instrument in accordance withthe present disclosure. Referring now to FIGS. 19A and 19B, in oneaspect the Hall-effect sensor 602 and magnet 608 configuration islocated on a shaft of a surgical instrument. In one aspect, the polefaces of the magnet 608 and the Hall-effect sensor 602 move in line withone another. In FIGS. 17A, 17B, 19A, and 19B, the Hall-effect sensor 602is stationary while the magnet 608 moves in connection with the clamparm. In one aspect, the inner threaded collar is configure to carry themagnet 608 and may be directly connected to the inner tube. In this way,the Hall-effect sensor 602 may be positioned in a different way on therotation knob such that the faces of the magnet 608 and the Hall-effectsensor 602 come together in a perpendicular manner as shown by themotion arrow 640.

In one aspect, an ultrasonic algorithm or process may be used to enablea surgical device to seal tissue without transection. The implementationof this algorithm or process may require measuring clamp arm positionrelative to the ultrasonic blade of an end effector. A method can beused to sense the clamp arm position relative to the ultrasonic blade asdescribed herein and that positioning can be consistently calibratedduring manufacturing, as will be described below, such that estimates ofthickness of tissue can be made. For example, an algorithm or processthat is fed information about quantity of tissue can react as thatquantity changes. This may allow the surgical device to treat the tissuewithout completely transecting a vessel.

Turning now briefly to FIG. 32, once the clamp arm position relative toultrasonic blade is known, how the ultrasonic blade vibrates can beadjusted to get different tissue effects. In this way, process 3200 mayadjust 3206 a power output to the ultrasonic blade of the end effectorbased on the clamp arm position. For example, process 3200 may adjust3214 the power output to the ultrasonic blade of the end effector usingan ultrasonic transducer based on a voltage change in a Hall-effectsensor.

Typically, end effectors may be used to coagulate and cuts vessels atthe same time. However, using the techniques and features describedherein, an end effector may be used to seal a carotid or vessel withoutactually transecting it, as may be desired by a surgeon. Withinformation on the clamp arm position, a Travel Ratio (TR) can becalculated, whereby if the clamp arm is in the completely closedposition with nothing captured in the end effector, the sensor (e.g.,Hall-effect sensor) may indicate a TR of 1. For example, forillustrative purposes only, let XT represent a relative clamp armposition at any given time in activation, X1 be a claim arm positionwhen the surgical device is fully clamped with no tissue, and X2 be aclamp arm position at a beginning of activation, with tissue grasped inthe end effector, where:

${TR} = \frac{{X1} - {XT}}{{X1} - {X2}}$

Continuing with the example above, X1 may be a value programmed into thesurgical device for the clamp arm position when the jaws are fullyclosed and nothing is captured in the end effector. X2 may be the clamparm position at the start of an activation such that if a vessel isattached in the end effector and the clamp arm is closed all the way,the clamp arm may be squeezing the vessel down but with some distance totravel before the vessel is transected and the clamp arm is directlyopposite the ultrasonic blade with full contact. XT may changedynamically as it is the clamp arm position at any given time.

For example, at the very beginning of activation TR may be zero, as X1may be set to represent the clamp arm position being fully closed withnothing captured. X2, at the very beginning of the activation, when theclamp arm is touching a vessel, may provide a relative thickness beforefiring the ultrasonic blade. XT may be the value in the equation that isupdating continuously with time as the clamp arm travels further andcompresses and starts to cut the tissue. In one aspect, it may bedesirable to deactivate (e.g., stop firing) the ultrasonic blade whenthe clamp arm has traveled 70% or 0.7. Thus, it may be empiricallydetermined beforehand that a desired TR is 0.7 of the way between theclamp arm being closed with a full bite of tissue and being fully closedwith nothing in between the clamp arm and ultrasonic blade.

The TR of 0.7 has been described for illustrative purposes only and maydepend on many parameters. For example, the desired TR for the point atwhich the ultrasonic blade will be shut-off may be based on vessel size.The TR may be any value observed to work for treating a given tissue orvessel without transection. Once the desired position is known, thevibrating of the ultrasonic blade may be adjusted based on the desiredposition. FIG. 20 is a graph 2000 of a curve 2002 depicting Travel Ratio(TR) along the y-axis, based on Hall-effect sensor output voltage, as afunction of Time (Sec) along the x-axis. As shown in FIG. 20, thedesired TR is 0.7, meaning that the ultrasonic blade is deactivated(e.g., stop firing) when the clamp arm has traveled 70% or 0.7. This isrelative to a clamp arm on a vessel with a ultrasonic blade firing wherethe desired end TR was 0.7. In the particular example of FIG. 20, theultrasonic blade was activated (e.g., firing) on a carotid and shut offat the TR of 0.7 after about 16 seconds.

In one aspect, it may be desirable to use a proportional-integralcontroller. FIG. 21 is a graph 2100 of a first curve 2102 depictingTravel Ratio (TR) along the left y-axis, based on Hall-effect sensoroutput voltage, as a function of Time (Sec) along the x-axis. A secondcurve 2104 depicts Power (Watts) along the right y-axis as a function ofTime (Sec) along the x-axis. The graph 2100 provides an example of whatcan be accomplished with a proportional-integral (PI) controller. TheTravel Ratio (TR)curve 2102 is represented on the graph 2100 by the linemarked “TRAVEL RATIO.” The goal or Desired Value for the Travel Ratiomay be 0.7, as shown by the line marked “DESIRED VALUE,” althoughvarious other values may be used. The Power output curve 2104 representspower through the ultrasonic blade and is shown and marked “POWER(WATTS).”

Turning now briefly to FIG. 32, there is shown the process 3200 mayadjust 3216 the power output to the ultrasonic blade of the end effectordynamically, based on the travel ratio that changes as the clamp armapproaches the ultrasonic blade. For example, as the clamp arm movestowards the ultrasonic blade and the Desired Value is approached, theamount of power output to the ultrasonic blade and into the tissue maybe reduced. This is because the ultrasonic blade will cut the tissuewith enough power. However, if the power being output is reduced overtime as the Desired Value is approached (where a full transection may berepresented by a Travel Ratio of 1), the chance that the tissue istransected may be drastically reduced. In this way, effective sealingmay be achieved without cutting the tissue as may be desired by thesurgeon.

Turning back to FIG. 21, there is shown the Power output curve 2104shown in FIG. 21 may represent the power applied with a drive signal toa transducer stack to activate (e.g., fire) the ultrasonic blade. ThePower value may be proportional to the movement of the clamp arm portionof the end effector and delivered to the tissue and the Power curve mayrepresent voltage and current applied to the ultrasonic transducer. Inone aspect, the ultrasonic generator (e.g., generator 102) may read thevoltage output data from the Hall-effect sensor and, in response, sendcommands for how much voltage and current to provide to the transducerto drive the ultrasonic blade as desired. As the clamp arm portion ofthe end effector is moved and the desired value is approached, theultrasonic blade may be forced to deliver less energy to the tissue andreduce the likelihood of cutting the tissue.

As the ultrasonic blade is powered, the ultrasonic blade will effect thetissue or the vessel such that friction at the interface of theultrasonic blade and the tissue causes heat to drive the moisture fromand dry out the tissue. During this process, the clamp arm portion isable to increasingly compress the tissue as the seal develops. As the TRincreases over time the tissue flattens by applying more pressure withthe clamp arm as the tissue dries out. In this way, a PI controller maybe used to cook the tissue from a beginning point (where TR=0) to acertain second position by controlling power output to effectively seallarge vessels. With the PI controller, as the TR approaches the DesiredValue, the ultrasonic device drops the power delivery (to the ultrasonicblade) to smoothly control the compression and coagulation of thetissue. This process has shown an ability to effectively seal vesselswithout transection. In this way, process 3200 may adjust 3218 the poweroutput to the ultrasonic blade of the end effector dynamically, using aproportional-integral (PI) controller, based on a travel ratio thatchanges as the clamp arm approaches the ultrasonic blade. It will beappreciated that PI control is not the only logic system through whichpower could be controlled. Many mathematical mappings exist toappropriately reduce power as a function of the Hall-effect sensor.Examples of other logic systems include PID controllers, proportionalcontrollers, fuzzy logic, neural networks, polynomials, Bayesiannetworks, among others.

FIG. 22 is a graph 2200 depicting how the PI controller works. TheProportional term may be an indication of the absolute differencebetween TR and the Desired Value for TR. TR approaches the DesiredValue, the effect of the proportional term may shrink and as a resultthe ultrasonic power (e.g., delivered by the ultrasonic blade) may bereduced. The Integral term, shown as the area 2202 under the curve, maybe an accumulation of error over a give section of time. For example, asshown above, the Integral term may not begin to accumulate until after 5seconds. After 5 seconds, the Integral term may begin to take effect andthe power to the ultrasonic blade may be increased. After about 9seconds, the reduction of the effect in the Proportional term mayoutweigh the effect of the increase in the Integral term causing thepower delivery to the ultrasonic blade to become reduced. In thisexample, a Desired Value of 0.7 for the TR was used, however, asdiscussed above, the TR value may be optimized for a specific devicealong with the Proportional and Integral terms of the controller.

In effect, the PI controller may indicate what the power output shouldbe based on the distance at any given time between the Travel Ratio andthe Desired Value. From that distance, the PI controller may output acertain value (e.g., 0.4). In the example of FIG. 22, at a moment intime (e.g., 1 second) the distance is based on the values assigned tothe P and I. This distance may be multiplied it by a constant thatrepresents P and result in 0.78. The generator may instruct the systemto send out 0.78 or send out, for example, 7.8 watts of power when thedistance between these two is a certain amount. As a result, the TRcurve approaches the Desired Value curve, and the distance reduces. Overtime, the amount of power the generator tells the system to senddecreases, which may be the desired outcome. However, this could alsomean that if only P and not I is used, when time approaches 15 seconds,there may not be enough power output to the tissue to complete the goal.This is where the I portion (integral portion) is calculated at a setperiod of time, which may be about five seconds. By calculating the area2202 under the curve (shown in FIG. 22 by hashed lines, captured betweenthe Desired Value and Travel Ratio over time) and in addition to the0.78, shown between 0 and 5 seconds, the I portion starts to add its ownamount of power to help the progression of the Travel Ratio to theDesired Value and make sure that it gets there in a somewhat timelymanner. For example, at five seconds, the I portion is not active, butas time progresses the I portion starts to calculate the area capturedbetween the two curves and adds that value (e.g., additional four watts)which is the area under the curve, in addition to the power coming fromthe Proportional value. Using these two calculations together mayprovide the Power curve (i.e., the power output) as shown in FIG. 22.The PI controller is configured to drive towards the seal effect in asomewhat timely manner.

In one aspect the techniques described herein may be employed to sealdifferent sizes of vessels (e.g., 5 mm, 6 mm, and 7 mm round vessels).The strength of the seals may be tested until the seal bursts andrecording the burst pressure. A higher burst pressure indicates astronger seal. In the case of an actual surgery, if a surgicalinstrument or device as described herein is used to seal a vessel theseal will not leak if it has a high associated burst pressure. In oneaspect, the burst pressures can be measured across different sizes ofvessels, e.g., 5 mm, 6 mm, and 7 mm round vessels, respectively.Typically, smaller vessels have higher burst pressure with largervessels, the burst pressure is decreased.

Turning now to FIG. 23, there is shown several vessels 2400 that weresealed using the techniques and features described herein (e.g., usingan ultrasonic blade and a Hall-effect sensor). Using the PI controlleras described above, 60 vessels were sealed. 58 vessels were sealedwithout transection.

In one aspect, it has been observed that activating a ultrasonic bladewith the clamp arm open may help to release tissue that may have stuckto the ultrasonic blade while being coagulated. Detecting a change insignal from a Hall-effect sensor may indicate when the user is openingthe clamp arm after device activation. This information may trigger thesystem to send a low level ultrasonic signal for a short period of time,in order to release any tissue stuck to the ultrasonic blade. Thisshort, sub-therapeutic signal may reduce the level of stickingexperienced by the user. This feature may be useful if a ultrasonicshear device were designed for multiple uses and the ultrasonic bladecoating began to wear off. In this way, the techniques and featuresdescribed herein may be used to reduce the amount of tissue sticking tothe ultrasonic blade.

A method for calibrating an end effector and Hall-effect sensor mayinclude calibrating the end effector and Hall-effect sensor duringmanufacturing of thereafter. As discussed above, process 3300 shown inFIG. 32, may be used to calibrate a controller for the end effector. Forexample, a clamp arm position of a ultrasonic device may be calibratedduring assembly. As discussed herein, sensing the position of the clamparm relative to the ultrasonic blade may provide relevant surgicaldevice information that may enable new capabilities, including but notlimited to the ability to sense a quantity or type of tissues which maybe clamped inside the jaws. Further, determinations about variousalgorithms to execute (e.g., such sealing a vessel without transection)may be made based on sensing the position of the clamp arm. However, invarious aspects, in order for this information to be useful andreliable, the surgical device must be calibrated in relation to abaseline such as when the clamp arm is fully open or when the clamp armfully closed with zero material in the end effector.

As described above, determining a Travel Ratio (TR) may help in variousprocesses to control an end effector. In determining TR, X1 is the clamparm position when the device is fully closed with no tissue. Determiningthe value (e.g., Hall effect signal) corresponding to X1 may be doneduring manufacturing and may be part of the calibration process.

Turning now to FIG. 24, there is shown a graph 2500 of a best fit curve2502 of Hall-effect sensor output voltage along the y-axis as a functionof absolute distance (in) along the x-axis for various positions of theclamp arm. The best fit curve 2502 is plotted based on the absolutedistance (in) of the clamp arm from the ultrasonic blade as listed inthe third column 1406 of the table 1400 shown in FIG. 14A and thecorresponding Hall-effect sensor output voltage listed in the fourthcolumn 1408 of the table 1400 shown in FIG. 14A as the clamp arm movesfrom a fully open position to a fully closed position in accordance withthe present disclosure.

Still with reference to FIG. 24, there is shown an example electricaloutput of a Hall-effect sensor configured to sense clamp arm position isshown. The Hall-effect sensor signal strength plotted againstdisplacement of the sensor (e.g., a magnet) may follow a parabolic shapeas shown by the best fit curve 2502. To calibrate the Hall-effectsensor, several readings of the sensor are taken at known baselinelocations. During calibration, the best fit curve 2502 as shown in FIG.24 may be analyzed to confirm that the Hall-effect sensor is readingeffectively based on readings made in a production setting. In this way,a Hall-effect sensor response corresponding to various positions of theclamp arm (e.g., fully open, fully closed, and discrete positionstherebetween) may be recorded to create a best fit curve duringproduction. Various data points may be recorded (e.g., four data points1-4 as shown in FIG. 24 or more as may be necessary) to create the bestfit curve 2502. For example, in a first position, a Hall-effect sensorresponse may be measured when the clamp arm is fully opened. In thisway, turning briefly to FIG. 32, the process 3300 shown in FIG. 32 maydetect 3302 a first measurement signal (e.g., a Hall-effect sensorresponse) corresponding to a fully open position of a clamp arm and aultrasonic blade of the end effector.

Turning back now to FIG. 24 in conjunction with FIG. 25, the four datapoints 1-4 represent voltage measured with a Hall-effect sensor as afunction of the gap between the clamp arm 2606 and the ultrasonic blade2608, as shown in FIG. 24. These data points 1-4 may be recorded asdescribed in connection with FIGS. 25-28. The first data point (1) isrecorded when the end effector 2600 is in the configuration shown inFIG. 25. The first data point (1) corresponds to the Hall-effect sensoroutput voltage recorded when the clamp arm 2606 is in the fully openedpositon relative to the ultrasonic blade 2608.

The second data point (2) is recorded when the end effector 2600 is inthe configuration shown in FIG. 26. To obtain an accurate gap betweenthe clamp arm 2606 and the ultrasonic blade 2808, a first gage pin 2602of known diameter is placed at a predetermined location within the jawsof the end effector 2600, e.g., between the clamp arm 2606 and theultrasonic blade 2608. As shown in FIG. 26, the first gage pin 2602 ispositioned between the distal end and the proximal end of the ultrasonicblade 2608 and is grasped between the clamp arm 2606 and the ultrasonicblade 2608 to set an accurate gap between the clamp arm 2606 and theultrasonic blade 2808. Once the clamp arm 2606 is closed to grasp thefirst gage pin 2602, the output voltage of the Hall-effect sensor ismeasured and recorded. The second data point (2) is correlated to thegap set between the clamp arm 2606 and the ultrasonic blade 2608 by thefirst gage pin 2602. In this way, the output voltage of the Hall-effectsensor is equated to the gap distance between the clamp arm 2606 and theultrasonic blade 2608. The second data point (2) is one of several datapoints to develop the polynomial to generate the best fit curve 2502shown in FIG. 24. The process 3300 described in FIG. 32 detects 3304 anactual Hall-effect sensor voltage and determines the gap between theclamp arm 2606 and the ultrasonic blade 2608 based on the best firstcurve 2502 (e.g., computing the polynomial).

The third data point (3) is recorded when the end effector 2600 is inthe configuration shown in FIG. 27. To obtain another accurate gapbetween the clamp arm 2606 and the ultrasonic blade 2808, the first gagepin 2602 is removed and a second gage pin 2604 of known diameter isplaced at a predetermined location within the jaws of the end effector2600, e.g., between the clamp arm 2606 and the ultrasonic blade 2608,that is different form the location of the first gage pin 2602. As shownin FIG. 27, the second gage pin 2604 is positioned between the distalend and the proximal end of the ultrasonic blade 2608 and is graspedbetween the clamp arm 2606 and the ultrasonic blade 2608 to set anaccurate gap between the clamp arm 2606 and the ultrasonic blade 2808.Once the clamp arm 2606 is closed to grasp the second gage pin 2602, theoutput voltage of the Hall-effect sensor is measured and recorded. Thethird data point (3) is correlated to the gap set between the clamp arm2606 and the ultrasonic blade 2608 by the second gage pin 2604. In thisway, the output voltage of the Hall-effect sensor is equated to the gapdistance between the clamp arm 2606 and the ultrasonic blade 2608. Thethird data point (3) is one of several data points to develop thepolynomial to generate the best fit curve 2502 shown in FIG. 24. Theprocess 3300 described in FIG. 32 detects 3304 an actual Hall-effectsensor voltage and determines the gap between the clamp arm 2606 and theultrasonic blade 2608 based on the best first curve 2502 (e.g.,computing the polynomial).

The fourth data point (4) is recorded when the end effector 2600 is inthe configuration shown in FIG. 28. To obtain the fourth data point (4),there are no gage pins 2602, 2604 placed between the clamp arm 2606 andthe ultrasonic blade 2608, but rather, the clamp arm 2606 is place inthe fully closed position relative to the ultrasonic blade 2608. Oncethe clamp arm 2606 is placed in the fully closed position, the outputvoltage of the Hall-effect sensor is measured and recorded. The fourthdata point (4) is correlated to the fully closed clamp arm 2606position. In this way, the output voltage of the Hall-effect sensor isequated to the fully closed clamp arm 2606 position relative to theultrasonic blade 2608. The fourth data point (4) is one of several datapoints to develop the polynomial to generate the best fit curve 2502shown in FIG. 24. The process 3300 described in FIG. 32 detects 3304 anactual Hall-effect sensor voltage and determines the gap between theclamp arm 2606 and the ultrasonic blade 2608 based on the best firstcurve 2502 (e.g., computing the polynomial).

Various configurations of gage pins may create known displacementsand/or angles between the clamp arm 2606 and the ultrasonic blade 2608of the end effector 2600. Using kinematics of a given clamparm/ultrasonic blade/shaft design and gage pins of known diameter, atheoretical displacement of the shaft assembly can be known at each ofthe, e.g., four or more positions. This information may be input, alongwith the voltage readings of the Hall-effect sensor, to fit a paraboliccurve (e.g., best fit curve 2502 as shown in FIG. 24), which may becomesa characteristic of each individual surgical device. This informationmay be loaded onto the surgical device via an EEPROM or otherprogrammable electronics configured to communicate with the generator(e.g., the generator 102 shown in FIG. 6) during use of the surgicaldevice.

The Hall-effect sensor signal response at, for example, the fourpositions of the clamp arm described above may be graphed and theresponses may be fit and entered into to a lookup table or developedinto a polynomial which may be used to set/calibrate the Hall-effectsensor such that when used by a surgeon, the end effector delivers thetissue effect desired. In this way, process 3300 may determine 3308 abest fit curve to represent signal strength (e.g., from Hall-effectsensor) as a function of sensor displacement (e.g., magnet displacement)based on at least the first, second, and third signals, the fully open,intermediate, and fully closed positions, and a dimension of the rigidbody. Process 3300 may also create 3310 a lookup table based on at leastthe first, second, and third signals, and the fully open, intermediate,and fully closed positions.

The positioning of the Hall-effect sensor/magnet arrangement in theconfigurations described above may be used to calibrate the surgicaldevice such that the most sensitive movements of the clamp arm 2606exist when the clamp arm 2606 is closest to the ultrasonic blade 2608.Four positions, corresponding to four data points (1-4), were chosen inthe example described above, but any number of positions could be usedat the discretion of design and development teams to ensure propercalibration.

In one aspect, the techniques and features described herein may be usedto provide feedback to a surgeon to indicate when the surgeon should usehemostasis mode for the vessel sealing procedure prior to engaging thecutting procedure. For example, hemostasis mode algorithm may bedynamically changed based on the size of a vessel grasped by the endeffector 2600 in order to save time. This may require feedback based onthe position of the clamp arm 2606.

FIG. 29A is a schematic diagram 3000 of surgical instrument 3002configured to seal small and large vessels in accordance with one aspectof the present disclosure. The surgical instrument 3002 comprises an endeffector 3004, where the end effector comprises a clamp arm 3006 and anultrasonic blade 3008 for treating tissue including vessels of varioussizes. The surgical instrument 3002 comprises a Hall-effect sensor 3010to measure the position of the end effector 3004. A closure switch 3012is provided to provide a feedback signal indicating whether the triggerhandle 3013 of the surgical instrument is in a fully closed position.

Turning now to FIG. 29B there is shown a diagram of an example range ofa small vessel 3014 and a large vessel 3016 and the relative position ofa clamp arm of the end effector in accordance with one aspect of thepresent disclosure. With reference to FIGS. 29A-B, The surgicalinstrument 3002 shown in FIG. 29A is configured to seal small vessels3014 having a diameter <4 mm and large vessels 3016 having a diameter >4mm and the relative position of the clamp arm 3006 when grasping smalland large vessels 3014, 3016 and the different voltage readings providedby the end effector 3010 depending on the size of the vessel.

FIGS. 29C and 29D are two graphs 3020, 3030 that depicts two processesfor sealing small and large vessels by applying various ultrasonicenergy levels for a different periods of time in accordance with oneaspect of the present disclosure. Ultrasonic energy level is shown alongthe y-axis and time (Sec) is shown along the x-axis. With reference nowto FIGS. 29A-C, the first graph 3020 shown in FIG. 29C shows a processfor adjusting the ultrasonic energy drive level of a ultrasonic blade toseal a small vessel 3014. In accordance with the process illustrated bythe first graph 3020 for sealing and transecting a small vessel 3014, ahigh ultrasonic energy (5) is applied for a first period 3022. Theenergy level is then lowered to (3.5) for a second period 3024. Finally,the energy level is raised back to (5) for a third period 3026 tocomplete sealing the small vessel 3014 and achieve transection and thenthe energy level is turned off. The entire cycle lasting about 5seconds.

With reference now to FIGS. 29A-D, the second graph 3030 shown in FIG.29D shows a process for adjusting the ultrasonic energy drive level of aultrasonic blade to seal a large vessel 3016. In accordance with theprocess illustrated by the second graph 3030 for sealing and transectinga large vessel 3016, a high ultrasonic energy (5) is applied for a firstperiod 3032. The energy level is then lowered to (1) for a second period3034. Finally, the energy level is raised back to (5) for a third period3036 to complete sealing the large vessel 3016 and achieve transectionand then the energy level is turned off. The entire cycle lasting about10 seconds.

Smaller vessels 3014 may be easier to seal at high burst pressurelevels. Thus, it may be desirable to sense and determine whether asmaller vessel 3014 (e.g., less than 4 mm) is clamped by the clamp arm3006, and if so, the ultrasonic energy level may not need to be droppedto 1. Instead, the energy level could be dropped less, to about 3.5 forexample, as shown by the first graph 3020 shown in FIG. 29C. This mayallow the surgeon to get through the vessel, coagulate it, and cut thevessel more quickly with knowledge that the process can go fasterbecause the vessel 3014 is slightly smaller. If the vessel 3016 islarger, (e.g., 4 mm or greater) a process that heats the vessel slowerand over a longer period of time may be more desirable, as shown by thesecond graph 3030 in FIG. 29D.

FIG. 30 is a logic diagram illustrating an example process 3100 fordetermining whether hemostasis mode should be used, in accordance withone aspect of the present disclosure. At the outset, the process 3100reads 3102 the signal from a Hall-effect sensor determine 3102 theposition of an end effector. The process 3100 then determines 3104 if afull closure switch of the surgical device is depressed, or if thehandle of the surgical device is fully closed. If the full closureswitch of the surgical device is not depressed and/or if the handle ofthe surgical device is not fully closed, the process 3100 may continueto read 3102 the Hall-effect sensor to determine the position of the endeffector. If the full closure switch of the surgical device isdepressed, or if the handle of the surgical device is fully closed, theprocess 3100 determines 3106 if the end effector position indicates avessel larger than 5 mm. If the end effector position does not indicatea vessel larger than 5 mm, and no system indicators are found 3108, theprocess 3100 may continue to read 3102 the Hall-effect sensor anddetermine the position of the end effector.

If the end effector position indicates a vessel larger than 5 mm, theprocess 3100 determines 3110 if the end effector position indicates avessel larger than 7 mm. If the end effector position does not indicatea vessel larger than 7 mm, the process 3100 indicates 3112 thathemostasis mode should be used. This condition may be indicated using avariety of auditory, vibratory, or visual feedback techniques including,for example, a green LED located on the surgical device (e.g., on top ofthe handle) may be enabled. If the end effector position does indicate avessel larger than 7 mm, the process 3100 indicates 3114 that the tissueshould not be taken (i.e., hemostasis mode should not be used) becausetoo much tissue has been captured by the end effector. This conditionmay be indicated using a variety of auditory, vibratory, or visualfeedback techniques including, for example, a red LED on the surgicaldevice (e.g., on top of the handle) may be enabled.

FIG. 31 is a logic diagram illustrating an example process 3200 for endeffector control in accordance with one aspect of the presentdisclosure. In one aspect Referring to FIG. 31, process 3200 detects3202 a signal (e.g., at a Hall-effect sensor) in response to movement ofa first tube relative to a second tube, the first tube driving movementof a clamp arm of the end effector. The first tube may be, for example,similar to reciprocating tubular actuating member 58 (FIGS. 3 and 4) andthe second tube may be, for example, similar to outer tubular sheath 56(FIGS. 3 and 4). In other words, as described in FIG. 31, the first tubemay be an inner tube and the second tube is an outer tube. The innertube may be moveable 3208 relative to the outer tube. The outer tube maybe static relative to the inner tube. The process 3200 detects 3210 thesignal using a Hall-effect sensor and a magnet positioned on the firsttube.

The process 3200 continues and determines 3204 a clamp arm position ofthe end effector relative to a ultrasonic blade of the end effectorbased on the signal (from, e.g., Hall-effect sensor voltage output).Once clamp arm position relative to ultrasonic blade is known, thevibrational mode of the ultrasonic blade can be adjusted to obtaindifferent tissue effects. In this way, the process 3200 adjusts 3206 apower output to the ultrasonic blade of the end effector based on theclamp arm position. For example, the process 3200 may adjust 3214 thepower output to the ultrasonic blade of the end effector using anultrasonic transducer based on a voltage change in a Hall-effect sensor.Alternatively, the process can effectively seal vessels withouttransection. In this way, the process 3200 may adjust 3218 the poweroutput to the ultrasonic blade of the end effector dynamically, using aproportional-integral controller, based on a travel ratio that changesas the clamp arm approaches the ultrasonic blade.

In another aspect, the process 3200 may adjust 3216 the power output tothe ultrasonic blade of the end effector dynamically, based on thetravel ratio that changes as the clamp arm approaches the ultrasonicblade. For example, as the clamp arm moves towards the ultrasonic bladeand a Desired Value (FIGS. 21 and 22) is approached, the amount of poweroutput to the ultrasonic blade and into the tissue may be reduced. Thisis because the ultrasonic blade will cut the tissue with enough power.However, if the power being output is reduced over time as the DesiredValue is approached (where a full transection may be represented by aTravel Ratio of 1), the chance that the tissue is transected may bedrastically reduced. In this way, effective sealing may be achievedwithout cutting the tissue as may be desired by the surgeon.

In one aspect, the process 3200 of FIG. 31 moves 3212 a magnetpositioned on the first tube relative to a Hall-effect sensor as thefirst tube drives movement of the clamp arm of the end effector. Theprocess 3200 then determines 3220 a type of tissue between the clamp armand the ultrasonic blade based on a signal (from, e.g., a Hall-effectsensor). Further, using a processor and/or memory, one or morealgorithms (e.g., for sealing a vessel without transection) may bechosen based on the thickness, quantity, or type of tissue determined tobe clamped inside the jaws. In response to determining that the type oftissue between the clamp and the ultrasonic blade is a large vessel, theprocess 3200 may reduce 3226 the power output to the ultrasonic blade ofthe end effector by an amount more than for a small vessel. Further, inresponse to determining that the type of tissue between the clamp andthe ultrasonic blade is a small vessel, the process 3200 may reduce 3224the power output to the ultrasonic blade of the end effector by anamount less than for a large vessel. In one aspect, instead of changingalgorithms for small vessels as described above, an indicator may beprovided to the surgeon to indicate the thickness of the tissue capturedin the end effector. In one aspect, the process 3200 adjusts 3222 thepower output to the ultrasonic blade of the end effector based on thetype of tissue.

FIG. 32 is a logic diagram illustrating an example process 3300 forcalibrating an apparatus for controlling for an end effector inaccordance with one aspect of the present disclosure. In one aspect, theprocess 3300 detects 3302 a first signal corresponding to a fully openposition of a clamp arm and a blade of the end effector. The process3300 then detects 3304 a second signal corresponding to an intermediateposition of the clamp arm and the blade of the end effector, theintermediate position resulting from clamping a rigid body between theclamp arm and the blade. The process detects 3306 a third signalcorresponding to a fully closed position of the clamp arm and the bladeof the end effector. Once the three signals are detected, the process3300 determines 3308 a best fit curve to represent signal strength as afunction of sensor displacement based on at least the first, second, andthird signals corresponding to the fully open, intermediate, and fullyclosed positions, respectively, and a dimension of the rigid body. Anexample of a best fit curve in this context is shown in FIGS. 14B and24. Finally, the process 3300 creates 3310 a lookup table based on atleast the first, second, and third signals corresponding to the fullyopen, intermediate, and fully closed positions, respectively.

As described hereinabove, the position of the clamp arm portion of theend effector can be measured with a Hall-effect sensor/magnetarrangement. A tissue pad, usually made of TEFLON, may be positioned onthe clamp arm to prevent tissue from sticking to the clamp arm. As theend effector is used and the tissue pad is worn, it will be necessary totrack the drift of the Hall-effect sensor output signal and establishchanging thresholds to maintain the integrity of the tissue treatmentalgorithm selection and the end of cut trigger points feedback to thetissue treatment algorithms.

Accordingly, a control system is provided. The output of the Hall-effectsensor in the form of counts can be used to track the aperture of theend effector clamp arm. The reader may refer to FIGS. 34 and 35 for ADCsystems 3500, 3600 that can employ the counter output of an ADC. Theclamp arm position, with or without a tissue pad, can be calibratedusing the techniques described herein. Once the clamp arm position iscalibrated, the position of the clamp arm and wear of the tissue pad canbe monitored. In one aspect, the control system determines that theclamp arm is in a closed position by monitoring for a rise in acousticimpedance that occurs when the ultrasonic blade contacts either tissueor the tissue pad. Thus, a specific number of ADC counter willaccumulate a specific number of counts from the time the clamp arm goesfrom a fully open position to a fully closed position. In oneimplementation, based on the configuration of the Hall-effect sensor,the Hall-effect sensor ADC counts increase as the clamp arm closestowards the ultrasonic blade. As the tissue pad wears, the counter willaccumulate an incremental additional number of counts due to theadditional rotational travel experienced by the clamp arm due to tissuepad wear. By tracking the new count value for a closed clamp armposition, the control system can adjust the trigger threshold for an endof cut and better predict the total range of aperture of the clamp armthat has occurred.

Furthermore, the Hall-effect sensor ADC counts may be employed todetermine the tissue coefficient of friction (μ) of the tissue undertreatment based on the aperture of the clamp arm by employingpredetermined μ values stored in a look-up table. For example, thespecific tissue treatment algorithm can be dynamically adjusted orchanged during an ultrasonic treatment cycle (e.g., firing sequence oractivation of ultrasonic energy) to optimize the tissue cut based on thetissue type (e.g., fatty tissue, mesentery, vessel) or the tissuequantity or thickness.

FIG. 33 is a logic diagram of a process 3400 for tracking wear of thetissue pad portion of the clamp arm and compensating for resulting driftof the Hall-effect sensor and determining tissue coefficient offriction, according to one aspect of the present disclosure. The process3400 may be implemented in software, hardware, firmware, or acombination thereof, employing the generator circuit environmentillustrated in connection with FIGS. 6-10.

In one aspect, the process 3400 may be implemented by a circuit maycomprising a controller comprising one or more processors (e.g.,microprocessor, microcontroller) coupled to at least one memory circuit.The at least one memory circuit stores machine executable instructionsthat when executed by the processor, cause the processor to execute theprocess 3400.

The processor may be any one of a number of single or multi-coreprocessors known in the art. The memory circuit may comprise volatileand non-volatile storage media. In one aspect, the processor may includean instruction processing unit and an arithmetic unit. The instructionprocessing unit may be configured to receive instructions from the onememory circuit.

In one aspect, a circuit may comprise a finite state machine comprisinga combinational logic circuit configured to implement the process 3400described herein. In one aspect, a circuit may comprise a finite statemachine comprising a sequential logic circuit comprising a combinationallogic circuit and at least one memory circuit, for example. The at leastone memory circuit can store a current state of the finite statemachine. The sequential logic circuit or the combinational logic circuitcan be configured to implement the process 3400 described herein. Incertain instances, the sequential logic circuit may be synchronous orasynchronous.

In other aspects, the circuit may comprise a combination of theprocessor and the finite state machine to implement the compression anddecompression techniques described herein. In other embodiments, thefinite state machine may comprise a combination of the combinationallogic circuit and the sequential logic circuit.

As described herein, the position of the clamp arm is sensed by aHall-effect sensor relative to a magnet located in a closure tube of asurgical instrument. Turning now to the process 3400, the initial homeposition of the clamp arm, e.g., the position of the Hall-effect sensorlocated on the closure tube, is stored 3402 in memory. As the closuretube is displaced in a distal direction, the clamp arm is closed towardsthe ultrasonic blade and the instantaneous position of the clamp arm isstored 3404 in memory. The difference, delta (x), between theinstantaneous position and the home position of the clamp arm iscalculated 3406. The difference, delta (x), may be used to determine achange in displacement of the tube, which can be used to calculate theangle and the force applied by the clamp arm to the tissue locatedbetween the clamp arm and the ultrasonic blade. The instantaneousposition of the clamp arm is compared 3408 to the closed position of theclamp arm determine whether the clamp arm is in a closed position. Whilethe clamp arm is not yet in a closed position, the process 3400 proceedsalong the no path (N) and compares the instantaneous position of theclamp arm with the home position of the clamp arm until the clampreaches a closed position.

When the clamp arm reaches a closed position, the process 3400 continuesalong the yes path (Y) and the closed position of the clamp arm isapplied to one input of a logic AND function 3410. The logic ANDfunction 3410 is a high level representation of a logic operation, whichmay comprise boolean AND, OR, XOR, and NAND operations implementedeither in software, hardware, or a combination thereof. When a tissuepad abuse or wear condition is determined based on acoustic impedancemeasurements, the current clamp arm closed position is set 3414 as thenew home position of the clamp arm to compensate for the abuse or wearcondition. If no tissue pad abuse or wear is determined, the homeposition of the clamp arm remains the same. Abuse or wear of the clamparm tissue pad is determined by monitoring 3420 the impedance 3422 ofthe ultrasonic blade. The tissue pad/ultrasonic blade interfaceimpedance id s determined 3422 and compared 3412 to a tissue pad abuseor wear condition. When the impedance corresponds to a tissue pad abuseor wear condition, the process 3400 proceeds along the yes path (Y) andthe current closed position of the clamp arm is set 3414 as the new homeposition of the clamp arm to compensate for the abuse or wear conditionof the tissue pad. When the impedance does not correspond to a tissuepad abuse or wear condition, the process 3400 proceeds along the no path(N) and the home position of the clamp arm remains the same.

The stored 3404 instantaneous position of the clamp arm is also providedto the input of another logic AND function 3416 to determine thequantity and thickness of the tissue clamped between the clamp arm andthe ultrasonic blade. The tissue/ultrasonic blade interface impedance isdetermined 3422 and is compared 3424, 34267, 3428 to multiple tissuecoefficients of friction μ=x, μ=y, or μ=z. Thus, when thetissue/ultrasonic blade interface impedance corresponds to one of thetissue coefficients of friction μ=x, μ=y, or μ=z based on the tissuequantity or thickness, e.g., the aperture of the clamp arm, the currenttissue algorithm is maintained 3430 and the current algorithm is usedfor monitoring 3420 the impedance 3422 of the ultrasonic blade. If thetissue coefficient of friction μ=x, μ=y, or μ=z based on the tissuequantity or thickness, e.g., the aperture of the clamp arm, changes, thecurrent tissue algorithm is changed 3418 based on the new tissuecoefficient of friction μ and the tissue quantity or thickness, e.g.,the aperture of the clamp arm and the new algorithm is used formonitoring 3420 the impedance 3422 of the ultrasonic blade.

Accordingly, the current clamp arm aperture is used to determine thecurrent tissue coefficient of friction μ based on the quantity andthickness of tissue as measured by the aperture of the clamp arm. Thus,an initial algorithm may be based on an initial aperture of the clamparm. The impedance of the ultrasonic blade is compared 3424, 3426, 3428to several tissue coefficients of friction μ=x, μ=y, or μ=z, which arestored in a look-up table, and correspond to fatty tissue, mesenterytissue, or vessel tissue, for example. If no match occurs between theimpedance of the ultrasonic blade and the tissue coefficient offriction, the process 3400 proceeds along the no paths (N) of any of thetissue impedance comparisons 3424, 3426, 3428 and the current tissuealgorithm is maintained. If any one of the outputs of the comparison3424, 3426, 3428 functions is true, the processor switches to adifferent tissue treatment algorithm based on the new tissue impedanceand clamp arm aperture. Accordingly, a new tissue treatment algorithm isloaded in the ultrasonic instrument. The process 3400 continues bymonitoring 3420 the impedance of the ultrasonic blade, clamp armaperture, and tissue pad abuse or wear.

FIG. 34 illustrates a Hall-effect sensor system 3500 that can beemployed with the process 3400 of FIG. 33, according to one aspect ofthe present disclosure. In connection with the process 3400 described inFIG. 33, the Hall-effect sensor system 3500 of FIG. 34 includes aHall-effect sensor 3502 powered by a voltage regulator 3504. The outputof the Hall-effect sensor 3502 is an analog voltage proportional to theposition of the clamp arm, which is applied to an analog-to-digitalconverter 3506 (ADC). The n-bit digital output of the ADC 3506 isapplied to a microprocessor 3508 coupled to a memory 3510. Themicroprocessor 3508 is configured to process and determine the positionof the clamp arm based on the n-bit digital input from the ADC 3505. Itwill be appreciated that the digital output of the ADC 3506 may bereferred to as a count.

As described herein, the analog output of the Hall-effect sensor isprovided to an internal or an external analog-to-digital converter suchas the ADC 3506 shown in FIG. 34 or any of the analog-to-digitalconverter circuits located in the generator. The transducer 104 shown inFIG. 6 may comprise an Hall-effect sensor comprising andanalog-to-digital converter circuit whose output is applied to thecontrol circuit 108. In one aspect, the generator 102 shown in FIG. 7comprises several analog-to-digital converter circuits such as ADCs 176,178, 180, which can be adapted and configured to receive the analogvoltage output of the Hall-effect sensor and convert it into digitalforms to obtain counts and to interface the Hall-effect sensor with aDSP processor 174, microprocessor 190, a logic device 166, and/or acontroller 196.

FIG. 35 illustrates one aspect of a ramp type counter analog-to-digitalconverter 3600 (ADC) that may be employed with the Hall-effect sensorsystem 3500 of FIG. 34, according to one aspect of the presentdisclosure. The digital ramp ADC 3600 receives an analog input voltagefrom a Hall-effect sensor at the Vin positive input terminal of acomparator 3602 and Dn through D0 (Dn-D0) are the digital outputs(n-bits). The control line found on a counter 3606 turns on the counter3606 when it is low and stops the counter 3606 when it is high. Inoperation, the counter 3606 is increased until the value found on thecounter 3606 matches the value of the analog input signal at Vin. Thedigital output Dn-D0 is applied to a digital-to-analog converter 3604(DAC) and the analog output is applied to the negative terminal of thecomparator 3602 and it is compared to the analog input voltage at Vin.When this condition is met, the value on the counter 3606 is the digitalequivalent of the analog input signal at Vin.

A START pulse is provided for each analog input voltage Vin to beconverted into a digital signal. The END signal represents the end ofthe conversion for each individual analog input voltage found at Vin(each sample), and not for the entire analog input signal. Each clockpulse increments the counter 3606. Supposing an 8-bit ADC, forconverting the analog value for “128” into digital, for example, itwould take 128 clock cycles. The ADC 3600 counts from 0 to the maximumpossible value (2n−1) until the correct digital output Dn-D0 value isidentified for the analog input voltage present at Vin. When this istrue, the END signal is given and the digital value for Vin is for atDn-D0.

While various aspects have been described herein, it should be apparent,however, that various modifications, alterations and adaptations tothose aspects may occur to persons skilled in the art with theattainment of some or all of the advantages of the invention. Thedisclosed aspects are therefore intended to include all suchmodifications, alterations and adaptations without departing from thescope and spirit of the invention. Accordingly, other aspects andimplementations are within the scope of the following claims. Forexample, the actions recited in the claims can be performed in adifferent order and still achieve desirable results.

While various details have been set forth in the foregoing description,it will be appreciated that the various aspects of the techniques foroperating a generator for digitally generating electrical signalwaveforms and surgical instruments may be practiced without thesespecific details. One skilled in the art will recognize that the hereindescribed components (e.g., operations), devices, objects, and thediscussion accompanying them are used as examples for the sake ofconceptual clarity and that various configuration modifications arecontemplated. Consequently, as used herein, the specific exemplars setforth and the accompanying discussion are intended to be representativeof their more general classes. In general, use of any specific exemplaris intended to be representative of its class, and the non-inclusion ofspecific components (e.g., operations), devices, and objects should notbe taken limiting.

Further, while several forms have been illustrated and described, it isnot the intention of the applicant to restrict or limit the scope of theappended claims to such detail. Numerous modifications, variations,changes, substitutions, combinations, and equivalents to those forms maybe implemented and will occur to those skilled in the art withoutdeparting from the scope of the present disclosure. Moreover, thestructure of each element associated with the described forms can bealternatively described as a means for providing the function performedby the element. Also, where materials are disclosed for certaincomponents, other materials may be used. It is therefore to beunderstood that the foregoing description and the appended claims areintended to cover all such modifications, combinations, and variationsas falling within the scope of the disclosed forms. The appended claimsare intended to cover all such modifications, variations, changes,substitutions, modifications, and equivalents.

For conciseness and clarity of disclosure, selected aspects of theforegoing disclosure have been shown in block diagram form rather thanin detail. Some portions of the detailed descriptions provided hereinmay be presented in terms of instructions that operate on data that isstored in one or more computer memories or one or more data storagedevices (e.g. floppy disk, hard disk drive, Compact Disc (CD), DigitalVideo Disk (DVD), or digital tape). Such descriptions andrepresentations are used by those skilled in the art to describe andconvey the substance of their work to others skilled in the art. Ingeneral, an algorithm refers to a self-consistent sequence of stepsleading to a desired result, where a “step” refers to a manipulation ofphysical quantities and/or logic states which may, though need notnecessarily, take the form of electrical or magnetic signals capable ofbeing stored, transferred, combined, compared, and otherwisemanipulated. It is common usage to refer to these signals as bits,values, elements, symbols, characters, terms, numbers, or the like.These and similar terms may be associated with the appropriate physicalquantities and are merely convenient labels applied to these quantitiesand/or states.

Unless specifically stated otherwise as apparent from the foregoingdisclosure, it is appreciated that, throughout the foregoing disclosure,discussions using terms such as “processing” or “computing” or“calculating” or “determining” or “displaying” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment). Those having skill in the art will recognize that thesubject matter described herein may be implemented in an analog ordigital fashion or some combination thereof.

The foregoing detailed description has set forth various forms of thedevices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, and/or examples can beimplemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof. Inone form, several portions of the subject matter described herein may beimplemented via an application specific integrated circuits (ASIC), afield programmable gate array (FPGA), a digital signal processor (DSP),or other integrated formats. However, those skilled in the art willrecognize that some aspects of the forms disclosed herein, in whole orin part, can be equivalently implemented in integrated circuits, as oneor more computer programs running on one or more computers (e.g., as oneor more programs running on one or more computer systems), as one ormore programs running on one or more processors (e.g., as one or moreprograms running on one or more microprocessors), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of skill in the art in light of this disclosure.In addition, those skilled in the art will appreciate that themechanisms of the subject matter described herein are capable of beingdistributed as one or more program products in a variety of forms, andthat an illustrative form of the subject matter described herein appliesregardless of the particular type of signal bearing medium used toactually carry out the distribution. Examples of a signal bearing mediuminclude, but are not limited to, the following: a recordable type mediumsuch as a floppy disk, a hard disk drive, a Compact Disc (CD), a DigitalVideo Disk (DVD), a digital tape, a computer memory, etc.; and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link (e.g., transmitter,receiver, transmission logic, reception logic, etc.), etc.).

In some instances, one or more elements may be described using theexpression “coupled” and “connected” along with their derivatives. Itshould be understood that these terms are not intended as synonyms foreach other. For example, some aspects may be described using the term“connected” to indicate that two or more elements are in direct physicalor electrical contact with each other. In another example, some aspectsmay be described using the term “coupled” to indicate that two or moreelements are in direct physical or electrical contact. The term“coupled,” however, also may mean that two or more elements are not indirect contact with each other, but yet still co-operate or interactwith each other. It is to be understood that depicted architectures ofdifferent components contained within, or connected with, differentother components are merely examples, and that in fact many otherarchitectures may be implemented which achieve the same functionality.In a conceptual sense, any arrangement of components to achieve the samefunctionality is effectively “associated” such that the desiredfunctionality is achieved. Hence, any two components herein combined toachieve a particular functionality can be seen as “associated with” eachother such that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated also can be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality,and any two components capable of being so associated also can be viewedas being “operably couplable,” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents, and/or wirelessly interactable, and/or wirelesslyinteracting components, and/or logically interacting, and/or logicallyinteractable components, and/or electrically interacting components,and/or electrically interactable components, and/or opticallyinteracting components, and/or optically interactable components.

In other instances, one or more components may be referred to herein as“configured to,” “configurable to,” “operable/operative to,”“adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Thoseskilled in the art will recognize that “configured to” can generallyencompass active-state components and/or inactive-state componentsand/or standby-state components, unless context requires otherwise.

While particular aspects of the present disclosure have been shown anddescribed, it will be apparent to those skilled in the art that, basedupon the teachings herein, changes and modifications may be made withoutdeparting from the subject matter described herein and its broaderaspects and, therefore, the appended claims are to encompass withintheir scope all such changes and modifications as are within the truescope of the subject matter described herein. It will be understood bythose within the art that, in general, terms used herein, and especiallyin the appended claims (e.g., bodies of the appended claims) aregenerally intended as “open” terms (e.g., the term “including” should beinterpreted as “including but not limited to,” the term “having” shouldbe interpreted as “having at least,” the term “includes” should beinterpreted as “includes but is not limited to,” etc.). It will befurther understood by those within the art that if a specific number ofan introduced claim recitation is intended, such an intent will beexplicitly recited in the claim, and in the absence of such recitationno such intent is present. For example, as an aid to understanding, thefollowing appended claims may contain usage of the introductory phrases“at least one” and “one or more” to introduce claim recitations.However, the use of such phrases should not be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to claims containing only one such recitation, even when thesame claim includes the introductory phrases “one or more” or “at leastone” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an”should typically be interpreted to mean “at least one” or “one ormore”); the same holds true for the use of definite articles used tointroduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should typically be interpreted to mean at least the recitednumber (e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that typically a disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms unless context dictates otherwise. For example, the phrase “Aor B” will be typically understood to include the possibilities of “A”or “B” or “A and B.”

With respect to the appended claims, those skilled in the art willappreciate that recited operations therein may generally be performed inany order. Also, although various operational flows are presented in asequence(s), it should be understood that the various operations may beperformed in other orders than those which are illustrated, or may beperformed concurrently. Examples of such alternate orderings may includeoverlapping, interleaved, interrupted, reordered, incremental,preparatory, supplemental, simultaneous, reverse, or other variantorderings, unless context dictates otherwise. Furthermore, terms like“responsive to,” “related to,” or other past-tense adjectives aregenerally not intended to exclude such variants, unless context dictatesotherwise.

It is worthy to note that any reference to “one aspect,” “an aspect,”“one form,” or “a form” means that a particular feature, structure, orcharacteristic described in connection with the aspect is included in atleast one aspect. Thus, appearances of the phrases “in one aspect,” “inan aspect,” “in one form,” or “in an form” in various places throughoutthe specification are not necessarily all referring to the same aspect.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner in one or more aspects.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

In certain cases, use of a system or method may occur in a territoryeven if components are located outside the territory. For example, in adistributed computing context, use of a distributed computing system mayoccur in a territory even though parts of the system may be locatedoutside of the territory (e.g., relay, server, processor, signal-bearingmedium, transmitting computer, receiving computer, etc. located outsidethe territory).

A sale of a system or method may likewise occur in a territory even ifcomponents of the system or method are located and/or used outside theterritory. Further, implementation of at least part of a system forperforming a method in one territory does not preclude use of the systemin another territory.

All of the above-mentioned U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications, non-patent publications referred to in this specificationand/or listed in any Application Data Sheet, or any other disclosurematerial are incorporated herein by reference, to the extent notinconsistent herewith. As such, and to the extent necessary, thedisclosure as explicitly set forth herein supersedes any conflictingmaterial incorporated herein by reference. Any material, or portionthereof, that is said to be incorporated by reference herein, but whichconflicts with existing definitions, statements, or other disclosurematerial set forth herein will only be incorporated to the extent thatno conflict arises between that incorporated material and the existingdisclosure material.

In summary, numerous benefits have been described which result fromemploying the concepts described herein. The foregoing description ofthe one or more forms has been presented for purposes of illustrationand description. It is not intended to be exhaustive or limiting to theprecise form disclosed. Modifications or variations are possible inlight of the above teachings. The one or more forms were chosen anddescribed in order to illustrate principles and practical application tothereby enable one of ordinary skill in the art to utilize the variousforms and with various modifications as are suited to the particular usecontemplated. It is intended that the claims submitted herewith definethe overall scope.

Various aspects of the subject matter described herein are set out inthe following numbered clauses:

1. A method for controlling an end effector, the method comprising:detecting a signal in response to movement of a first tube relative to asecond tube, the first tube driving movement of a clamp arm of the endeffector; determining a clamp arm position of the end effector relativeto a ultrasonic blade of the end effector based on the signal; andadjusting a power output to the ultrasonic blade of the end effectorbased on the clamp arm position.

2. The method of clause 1, wherein adjusting the power output to theultrasonic blade is achieved by manipulating the electrical current sentto the handpiece.

3. The method of clause 1 or 2, wherein the first tube is an inner tubeand the second tube is an outer tube, the inner tube being moveablerelative to the outer tube, the outer tube being static relative to theinner tube.

4. The method of any one of clause 1 or 2, wherein the first tube is aninner tube and the second tube is an outer tube, the outer tube beingmoveable relative to the inner tube, the inner tube being staticrelative to the inner tube.

5. The method of any one of clauses 1-4 further comprising detecting thesignal using a Hall-effect sensor and a magnet positioned on the firsttube.

6. The method of any one of clauses 1-5, further comprising moving amagnet positioned on the first tube relative to a Hall-effect sensor asthe first tube drives movement of the clamp arm of the end effector.

7. The method of any one of clauses 1-6, further comprising adjustingthe power output to the ultrasonic blade of the end effector using anultrasonic transducer based on a voltage change in a Hall-effect sensor.

8. The method of any one of clauses 1-7, further comprising adjustingthe power output to the ultrasonic blade of the end effectordynamically, based on a travel ratio that changes as the clamp armapproaches the ultrasonic blade.

9. The method of any one of clauses 1-8, further comprising adjustingthe power output to the ultrasonic blade of the end effectordynamically, using a proportional-integral controller, based on a travelratio that changes as the clamp arm approaches the ultrasonic blade.

10. The method of any one of clauses 1-9, further comprising switchingoff completely the power output to the ultrasonic blade of the endeffector once a travel ratio threshold has been met.

11. The method of any one of clauses 1-10, further comprising:determining a quantity or thickness of tissue between the clamp arm andthe ultrasonic blade based on the signal; and adjusting the power outputto the ultrasonic blade of the end effector based on the quantity orthickness of tissue.

12. The method of clause 11, further comprising in response todetermining that the quantity or thickness of tissue between the clamparm and the ultrasonic blade is less than a predetermined threshold,reducing the power output to the ultrasonic blade of the end effector byan amount less than for a larger quantity or thickness of tissue.

13. The method of clause 11 or 12, further comprising in response todetermining that the quantity or thickness of tissue between the clamparm and the ultrasonic blade is above a predetermined threshold ,reducing the power output to the ultrasonic blade of the end effector byan amount more than for a smaller quantity or thickness of tissue.

14. An apparatus for controlling an end effector, the apparatuscomprising: a sensor configured to detect a signal in response tomovement of a first tube relative to a second tube, the first tubedriving movement of a clamp arm of the end effector; a processorconfigured to determine a clamp arm position of the end effectorrelative to a ultrasonic blade of the end effector based on the signal;and a transducer configured to adjust a power output to the ultrasonicblade of the end effector based on the clamp arm position.

15. The apparatus of clause 14, wherein the first tube is an inner tubeand the second tube is an outer tube, the outer tube being moveablerelative to the inner tube, the inner tube being static relative to theouter tube.

16. The apparatus of clause 14, wherein the first tube is an inner tubeand the second tube is an outer tube, the inner tube being moveablerelative to the outer tube, the outer tube being static relative to theinner tube.

17. The apparatus of any one of clauses 14-16, further comprising: amagnet positioned on the first tube; and wherein the sensor is aHall-effect sensor used to detect the signal based on a position of themagnet.

18. The apparatus of any one of clauses 14-17, wherein the magnetpositioned on the first tube moves relative to a Hall-effect sensor asthe first tube drives movement of the clamp arm of the end effector.

19. The apparatus of any one of clauses 14-18, wherein the transducer isan ultrasonic transducer configured to adjust the power output to theultrasonic blade of the end effector based on a voltage change in aHall-effect sensor.

20. The apparatus of any one of clauses 14-19, wherein the transducer isconfigured to adjust the power output to the ultrasonic blade of the endeffector dynamically, based on a travel ratio that changes as the clamparm approaches the ultrasonic blade.

21. The apparatus of any one of clauses 14-20, further comprising: aproportional-integral controller configured to adjust the power outputto the ultrasonic blade of the end effector dynamically, based on atravel ratio that changes as the clamp arm approaches the ultrasonicblade.

22. A method for calibrating an apparatus for controlling an endeffector, the method comprising: detecting a first signal correspondingto a fully open position of a clamp arm and a ultrasonic blade of theend effector; detecting a second signal corresponding to an intermediateposition of the clamp arm and the ultrasonic blade of the end effector,the intermediate position resulting from clamping a rigid body betweenthe clamp arm and the ultrasonic blade; and detecting a third signalcorresponding to a fully closed position of the clamp arm and theultrasonic blade of the end effector.

23. The method of clause 22, further comprising: determining a best fitcurve to represent signal strength as a function of sensor displacementbased on at least the first, second, and third signals, the fully open,intermediate, and fully closed positions, and a dimension of the rigidbody.

24. The method of clause 22 or 23, further comprising: creating a lookuptable based on at least the first, second, and third signals, and thefully open, intermediate, and fully closed positions.

1-24. (canceled)
 25. An apparatus for controlling an end effectorcomprising a clamp arm, the apparatus comprising: a sensor configured togenerate signals in response to movement of a first tube relative to asecond tube, the first tube driving movement of the clamp arm of the endeffector; a control circuit configured to: receive a first signal,second signal, and a third signal from the sensor, wherein the firstsignal, the second signal, and the third signal are associated withpositions of the clamp arm of the end effector as it moves; generate afit curve based on the first signal, the second signal, and the thirdsignal; receive a fourth signal from the sensor, wherein the fourthsignal is associated with a current position of the clamp arm of the endeffector as it moves; and generate a conclusion associated with arelative position of the clamp arm based on the fourth signal and thegenerated fit curve.
 26. The apparatus of claim 25, wherein the endeffector further comprises an ultrasonic blade, and wherein the controlcircuit is further configured to: determine an impedance of theultrasonic blade in contact with the tissue; and determine a type of thetissue based on the impedance.
 27. The apparatus of claim 26, whereinthe generated conclusion comprises an estimated gap between the clamparm and the ultrasonic blade.
 28. The apparatus of claim 27, wherein theapparatus further comprises a transducer configured to dynamicallyadjust a power output to the ultrasonic blade of the end effector duringan ultrasonic treatment, to adjust a tissue cut based on the estimatedgap and the type of the tissue.
 29. The apparatus of claim 26, whereinthe first signal is associated with an open position of the clamp armrelative to the ultrasonic blade, wherein the second signal isassociated with an intermediate position of the clamp arm relative tothe ultrasonic blade, and wherein the third signal is associated with anclosed position of the clamp arm relative to the ultrasonic blade. 30.The apparatus of claim 25, wherein the control circuit is furtherconfigured to calibrate signals generated by the sensor during movementof the clamp arm of the end effector based on the generated fit curve toconfirm that the sensor is generating accurate signals.
 31. Theapparatus of claim 30, wherein the calibration comprises a comparison ofthe fourth signal to the generated fit curve.
 32. The apparatus of claim25, wherein generation of the fit curve comprises computing a polynomialbased on the first signal, the second signal, and the third signal. 33.The apparatus of claim 32, wherein generation of the conclusioncomprises computing a polynomial based on the generated fit curve andthe fourth signal.
 34. The method of claims 33, wherein the fit curvecomprises a parabola.
 35. The apparatus of claim 25, wherein the sensoris a Hall-effect sensor, and wherein the first signal, second signal,third signal, and fourth signal correspond to voltages detected by theHall-effect sensor.
 36. An apparatus for controlling an end effectorcomprising a clamp arm and an ultrasonic blade, the apparatuscomprising: a sensor configured to generate signals in response tomovement of a first tube relative to a second tube, the first tubedriving movement of the clamp arm of the end effector; a control circuitconfigured to: receive a first signal, second signal, and a third signalfrom the sensor, wherein the first signal, the second signal, and thethird signal are associated with positions of the clamp arm of the endeffector as it moves; generate a fit curve based on the first signal,the second signal, and the third signal; receive a fourth signal fromthe sensor, wherein the fourth signal is associated with a currentposition of the clamp arm of the end effector as it moves; generate aconclusion associated with a relative position of the clamp arm based onthe fourth signal and the generated fit curve; determine an impedance ofthe ultrasonic blade in contact with the tissue; and determine a type ofthe tissue based on the impedance.
 37. The apparatus of claim 36,wherein the generated conclusion comprises an estimated gap between theclamp arm and the ultrasonic blade.
 38. The apparatus of claim 38,wherein the apparatus further comprises a transducer configured todynamically adjust a power output to the ultrasonic blade of the endeffector during an ultrasonic treatment, to adjust a tissue cut based onthe estimated gap and the type of the tissue.
 39. The apparatus of claim36, wherein the first signal is associated with an open position of theclamp arm relative to the ultrasonic blade, wherein the second signal isassociated with an intermediate position of the clamp arm relative tothe ultrasonic blade, and wherein the third signal is associated with anclosed position of the clamp arm relative to the ultrasonic blade. 40.The apparatus of claim 36, wherein the control circuit is furtherconfigured to calibrate signals generated by the sensor during movementof the clamp arm of the end effector based on the generated fit curve toconfirm that the sensor is generating accurate signals.
 41. Theapparatus of claim 40, wherein the calibration comprises a comparison ofthe fourth signal to the generated fit curve.
 42. The apparatus of claim36, wherein generation of the fit curve comprises computing a polynomialbased on the first signal, the second signal, and the third signal. 43.The apparatus of claim 36, wherein generation of the conclusioncomprises computing a polynomial based on the generated fit curve andthe fourth signal.
 44. The apparatus of claim 36, wherein the fit curvecomprises a parabola.
 45. An computer-implemented method of controllingan end effector comprising a clamp arm and an ultrasonic blade, themethod comprising: receiving, via a control circuit, a first signal,second signal, and a third signal from a sensor configured to generatesignals in response to movement of a first tube of the end effectorrelative to a second tube of the end effector, the first tube drivingmovement of the clamp arm of the end effector, wherein the first signal,the second signal, and the third signal are associated with positions ofthe clamp arm of the end effector as it moves; generating, via thecontrol circuit, a fit curve based on the first signal, the secondsignal, and the third signal; receiving, via the control circuit, afourth signal from the sensor, wherein the fourth signal is associatedwith a current position of the clamp arm of the end effector as itmoves; generating, via the control circuit, a conclusion associated witha relative position of the clamp arm based on the fourth signal and thegenerated fit curve; determining, via the control circuit, a thicknessof a tissue based on the generated conclusion; determining, via thecontrol circuit, an impedance of the ultrasonic blade in contact withthe tissue; and determining, via the control circuit, a type of thetissue based on the impedance.